Language：English   Publishing type：Research paper (scientific journal)   Publisher：American Chemical Society  

Benzimidazolium naphthoxide (-ONap-BI+) was first synthesized and utilized as an unprecedented betaine photoredox catalyst. Photoexcited state of -ONap-BI+ generated by visible light irradiation catalyzes the reductive deiodination as well as desulfonylation reactions in which 1,3-dimethyl-2-phenylbenzimidazoline (Ph-BIH) cooperates with as an electron and hydrogen atom donor. Significant solvent effects on the reaction progress were discovered, and specific solvation toward imidazolium and naphthoxide moieties of -ONap-BI+ was proposed.

DOI： 10.1021/acs.joc.8b00282

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：JAPAN SOC HORTICULTURAL SCI  

Various on-tree ethanol-sticker treatments for 'Taigetsu' and 'Taiten' persimmon (astringent cultivars) were tested to identify optimal treatment conditions for astringency removal and fruit quality. Using aluminum foil coated or polyethylene terephthalate stickers to attach a pad containing 1.5 g of ethanol powder to both sides of the fruit surface in early October removed astringency completely, while the application of treatments to one side of the fruit surface did not. The astringency removal was incomplete in treatments with a cast coating sticker. The aluminum foil-coated sticker with a 1.0 g ethanol pad applied in early October removed flesh astringency completely without fruit skin darkening or the occurrence of large numbers of brown specks in the flesh. It extended fruit shelf life by approximately 7 days compared with postharvest CO2 treatment in November. Conversely, sticker treatments in late September caused many brown specks in the flesh. The sticker treatment with a 0.6 g ethanol pad failed to remove the astringency completely while the sticker treatment with a 1.5 g ethanol pad resulted in heavy fruit skin darkening or the appearance of shallow concentric cracks on the fruit skin. Therefore, we conclude that an on-tree sticker treatment with a 1.0 g ethanol pad on both sides of the fruit surface in early October removes fruit astringency completely and provides high quality 'Taigetsu' and 'Taiten' persimmon fruit.

DOI： 10.2503/hortj.OKD-039

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：PERGAMON-ELSEVIER SCIENCE LTD  

Visible light promoted reduction reactions of organohalides, sulfonamides, organonitriles and epoxy ketones were performed using 1,3-diinethylbenzimidazolines possessing 2-hydroxynaphthyl or 2-hydroxyphenyl substituents (HOAr-DMBIH) as photo-reductants. Xe or Hg-Xe lamp through an appropriate glass-filter (lambda>390 nm) and a household white light-emitting diode were used as light sources. In these reactions, reductive cleavages of carbon halogen, nitrogen sulfur, carbon carbon (nitrile) and carbon oxygen bonds take place. Bases exert significant effects on the progress of these reactions in a manner that depends on the nature of the substrate. Addition of 1,8-diazabicyclo[5.4.0]undec-7-ene as well as potassium t-butoxide significantly accelerates photo-reduction reactions of organohalides, sulfonamides and organonitriles while the decomposition of formed hydroxy ketones occurs in reactions of epoxy ketones. Single electron transfer from the photo-excited states of benzimidazolines (HOAr-DMBIH) or their deprotonated analogues (-OAr-DMBIH) to the substrates is proposed to initiate these reactions. (C) 2016 Elsevier Ltd. All rights reserved.

DOI： 10.1016/j.tet.2016.05.078

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：AMER CHEMICAL SOC  

Oxidative ring-opening reactions of benzene-fused bicyclic cydopropyl silyl ethers, promoted by copper(II) tetrafluoroborate, were investigated. The regioselectivity of cyclopropane ring-opening as well as product distributions were found to be highly dependent on the nature of the solvent. In alcohols, dimeric substances arising from external bond cleavage are major products. Radical rearrangement products are also formed in solvents such as ether and ethyl acetate. On the contrary, nucleophile addition to carbocation intermediates, generated by internal bond cleavage, occurs mainly in reactions taking place in acetonitrile. It is proposed that the observed solvent effects that govern the reaction pathways followed are a consequence of varying solvation of copper intermediates, which governs their reactivity and redox properties. In addition, the influence of counteranions of the copper salts, organonitriles, cyclic dienes, and substrate structures on the pathways followed in these reactions was also examined.

DOI： 10.1021/acs.joc.5b02827

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ROYAL SOC CHEMISTRY  

[5]Catenanes were synthesized by olefin metathesis dimerization. The reaction of pseudorotaxanes, which were derived from a [2]catenane and one equivalent of an ammonium salt bearing two terminal olefins in dichloromethane, with a catalytic amount of Grubbs catalyst afforded linear [5]catenanes in 12% yield. Intermolecular and intramolecular olefin metathesis reactions were controlled by the length of the alkyl chain of the ammonium salts.

DOI： 10.1039/c5cc07562a

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Photoinduced electron transfer (PET) reactions promoted by 2-aryl substituted 1,3-dimethylbenzimidazolines (Ar-DMBIH) were investigated. Excited states of Ar-DMBIH, formed by irradiation using light above 360 initiate PET reductions of various organic substrates, including transformations of epoxy ketones to aldols, free radical rearrangements such as the Dowd-Beckwith ring-expansion and 5-exo hexenyl cyclization, deprotection of N-sulfonyl-indols, and allylation of acyl formates. In these processes, Ar-DMBIH possessing 1-naphthyl, 2-naphthyl, 1-pyrenyl and 9-anthryl substituents formally act as two electron and one proton donors while the hydroxynaphthyl substituted derivative serves as a two electron and two proton donor. On the basis of the results of absorption spectroscopy studies, cyclic voltammetry and DFT calculation, a mechanistic sequence for these reduction reactions is proposed that involves initial photoexcitation of the aryl chromophore of the Ar-DMBIH followed by single electron transfer (SET) to the organic substrate to generate the radical cation of benzimidazoline and the radical anion of the substrate. (C) 2015 Elsevier Ltd. All rights reserved.

DOI： 10.1016/j.tet.2015.06.071

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：AMER CHEMICAL SOC  

A new sequential, one-pot protocol for transforming 1,3-disubstituted 2,3-epoxy ketones to beta-hydroxy ketones and alpha-methylene ketones has been developed. Reaction of epoxy ketones with boron trifluoride etherate ((BF3OEt2)-O-.) generates the cationic intermediates by regioselective epoxide ring opening and an acyl shift. Then, a treatment of these cations with 2-aryl-1,3-dimethylbenzimidazolines (DMBIH) results in formation of 1,2-disubstituted 3-hydroxy ketones. DMBIH serves as a hydride donor in the second step of this process. Finally, the beta-hydroxy ketones can be converted to 1,2-disubstituted 2-methylene ketones by treatment with methanesulfonic acid or a combination of methanesulfonyl chloride and triethylamine. Importantly, the sequential steps involved in formation of the alpha-methylene ketone products can be carried out in one pot.

DOI： 10.1021/jo5025249

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：CSIRO PUBLISHING  

The visible light-promoted reduction reactions of some organohalides were investigated using 2-aryl-1,3-dimethylbenzimidazolines (Ar-DMBIH) possessing 2-naphthyl or 2-hydroxynaphthyl substituents. In these reduction reactions, singleelectron transfer from photo-excited Ar-DMBIH, attained by Xe lamp irradiation through an appropriate glass-filter (lambda > 390 nm), to the halide substrates leads to the carbon-halogen bond cleavage, followed by the rearrangements of the formed carbon radicals such as 5-exo hexenyl cyclization and the Dowd-Beckwith ring expansion. Addition of 1,8-diazabicyclo[5.4.0] undec-7-ene was found to enhance the reducing ability of hydroxynaphthyl-substituted DMBIH. A household white light-emitting diode was also used as a light source for these reactions.

DOI： 10.1071/CH15396

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Copper(II)-acid catalyzed cyclopropanation of electron-rich alkenes, such as 1,3-dienamides, with cc-aryl diazoesters are described. The reaction could be performed without rare metal catalysts, excess substrate, or the need for the slow addition of the diazoesters. (C) 2014 Elsevier Ltd. All rights reserved.

DOI： 10.1016/j.tetlet.2014.03.115

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A combination of 2-aryl substituted 1,3-dimethyl-benzimidazolines (DMBIHs) and tris(2,2'-bipyridine) ruthenium(II) chloride, Ru(bpy)(3)Cl-2 was used to promote photoinduced electron-transfer (PET) reactions of alpha-halomethyl-substituted benzocyclic 1-alkanones. This photo-reagent system stimulates free radical forming, cleavage of both carbon-bromine and carbon-chlorine bonds that are not activated by carbonyl groups. The resulting free radicals undergo 5-exo hexenyl cyclization as well as sequential cyclization and ring-expansion (Dowd-Beckwith) reactions to form radicals that abstract hydrogen atoms from the radical cation of DMBIH to yield the observed products. The results of a study of the effects of substituents located on the 2-aryl ring of DMBIH suggest that steric and hydrogen-bonding interactions influence the nature of the reaction pathways followed by the radical intermediates. PET reactions using an iridium complex and DMBIH were also investigated. (C) 2014 Elsevier Ltd. All rights reserved.

DOI： 10.1016/j.tet.2014.02.078

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ROYAL SOC CHEMISTRY  

The base-induced asymmetric [2,3] Stevens rearrangement of N-cinnamyl tetraalkylammonium ylides derived from L-alanine amides proceeds via a double axially chiral intermediate to afford the corresponding alpha-substituted alanine derivatives with high enantio-and diastereoselectivities.

DOI： 10.1039/c4cc02536a

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A photoreaction between benzoyl compounds, such as benzoylformate derivatives, and 2-(p-anisyl)-1,3-dimethylbenzimidazoline in the presence of allyl bromide was found to give various allylated alcohols. In the reaction of benzoylformates, cc-hydroxy ester enolates, for which the negative charge occurs on the carbonyl carbon of benzoyl (umpolung reactivity), are proposed to be generated as intermediates by electron-transfer from benzimidazolines to the photoexcited benzoylformates; these species react with allyl bromide to produce alpha-allyl-alpha-hydroxy esters. (C) 2013 Elsevier Ltd. All rights reserved.

DOI： 10.1016/j.tetlet.2013.10.028

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：BEILSTEIN-INSTITUT  

Copper(II)-salt-promoted oxidative ring-opening reactions of bicyclic cyclopropanol derivatives were investigated. The regioselectivities of these processes were found to be influenced by the structure of cyclopropanols as well as the counter anion of the copper(II) salts. A mechanism involving rearrangement reactions of radical intermediates and their competitive trapping by copper ions is proposed.

DOI： 10.3762/bjoc.9.156

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：AMER CHEMICAL SOC  

The syntheses of [2]- and [3]catenanes by olefin metathesis and oxidative acetylide coupling have been studied in detail. Pseudorotaxanes that were obtained by mixing crown ether and ammonium salts containing two terminal reactive end-groups were converted to [2]- and [3]catenane. Their yields were influenced not only by the chain length of the ammonium salts but also by the concentration of the crown ether and the ammonium salts. The strain energies of [2]catenane were responsible for the formation of [2]catenane.

DOI： 10.1021/jo400239h

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The 1,4-elimination reaction of (Z)-N-Boc-2-(4-methoxy-2-alkenyloxy)amines with Bronsted acids catalyzed aza-Ferrier reaction of the 1,4-eliminated product, thus obtained, afforded various beta-amino-beta,gamma-unsaturated aldehydes. The scope and limitation of this sequential reaction are described. (C) 2013 Elsevier Ltd. All rights reserved.

DOI： 10.1016/j.tet.2013.01.088

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A unique and simple preparative method for N-cyano-alpha-arylpipecolinic acid esters via base-induced Sommelet-Hauser rearrangement, the von Braun reaction, and intramolecular alpha-alkylation is reported. The removal of the N-cyano substituent was achieved by hydrogenation and hydride reduction.

DOI： 10.3987/COM-12-12619

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Aza-Prins cyclization reactions of N-tosyl-3-butenylamine with p-methoxybenzaldehyde, 1-naphthaldehyde and 2-naphthaldehyde take place efficiently using a combination 1-butyl-3-methylimidazolium of ferric chloride and hexafluorophosphate in benzotrifluoride (Felm-BTF procedure). The new methodology, leading to formation of target N-tosyl-4-chloro-2-substituted piperidines, is superior to the one using 1-butyl-3-methylimidazolium tetrachloroferrate. The Felm-BTF procedure was also applied to aza-Prins cyclization reactions of other aldehydes. Finally, the effects of imidazolium salts on aza-Prins cyclization reaction promoted by boranetrifluoride-diethyl ether complex, leading to formation of fluorinated piperidines, were explored.

DOI： 10.3987/COM-12-S(N)78

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The intermolecular aromatic substitution of N,N-dialkylanilines and alkoxybenzenes with diazoesters is shown to proceed in the presence of catalytic amounts of both copper(II) salt and acid (Lewis or Bronsted). This method is a mild and rare metal-free C-C bond formation reaction between aromatic (sp(2)) and aliphatic (sp(3)) carbons. (C) 2012 Elsevier Ltd. All rights reserved.

DOI： 10.1016/j.tetlet.2012.07.070

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Selective amine de-alkylation enables the conversion of Sommelet-Hauser rearrangement products into 2-aryl-2-bromoacetic acid derivatives. These compounds are valuable synthetic intermediates in the synthesis of alpha-aryl-alpha-amino or alpha-aryl-beta-amino acid derivatives. The method presented herein is a formal de-N,N-dialkylation of Sommelet-Hauser rearrangement products. (C) 2012 Elsevier Ltd. All rights reserved.

DOI： 10.1016/j.tet.2012.04.015

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A new protecting group, 1,2-dimethoxy-4,5-dimethylene, for acyclic amino acid derivatives could be introduced by N,N-dialkylation with 1,2-bis(bromomethyl)-4,5-dimethoxybenzene (1) and removed via amine de-alkylation with acyl chlorides. The method can be used with base-induced [2,3] and [1,2] Stevens rearrangement products. (C) 2012 Elsevier Ltd. All rights reserved.

DOI： 10.1016/j.tetlet.2012.01.013

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Asymmetric alpha-2-tosylethenylation of (S)-2-(pyrrolidin-1-yl)propanoic acid esters was shown to produce good yields with high enantioselectivities. The reaction proceeds via the formation of a non-racemic ammonium enolate without an external source of chirality.

DOI： 10.1039/c1ob06074k

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Asymmetric alpha-2-tosylvinylation of N-substituted proline esters using ethynyl tolyl sulfone as an electrophile was shown to proceed in good yield with high enantioselectivities without the addition of any bases. The reaction proceeds via the formation of N-2-tosylvinyl ammonium ylides. (C) 2011 Elsevier Ltd. All rights reserved.

DOI： 10.1016/j.tetlet.2011.02.040

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We developed a metalloporphyrin-based molecular container capped with a calix[4] arene, and its rigid cavity distinguished the slight structural differences in the aromatic guests.

DOI： 10.1039/c1cc14739k

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：WILEY-BLACKWELL  

The intermolecular aromatic substitution of N,N-disubstituted anilines with diazo esters is achieved under mild conditions in the presence of a catalytic amount of copper(II) triflate (up to 89% yield). The scope and limitations regarding substrates, diazo esters, and ligands in this reaction are described.

DOI： 10.1002/ejoc.201001083

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Aza-Prins cyclization reaction of N-tosyl-3-butenylamine with aliphatic and aromatic aldehydes was performed using a combination of FeCl3 and 1-butyl-3-methylimidazolium hexafluorophosphate (BmimPF(6)) or 1-butyl-3-methylimidazolium tetrachloroferrate (BmimFeCl(4)) in benzotrifluoride (BTF). The desired N-tosyl-4-chloro-2-substituted piperidines were obtained from aliphatic aldehydes in comparable yields to those for the previously reported reactions in which FeCl3 was used in CH2Cl2. On the other hand, significant progress for the piperidine synthesis from aromatic aldehydes has been achieved, particularly when BmimFeCl(4) was used with FeCl3 in BTF. (C) 2010 Elsevier Ltd. All rights reserved.

DOI： 10.1016/j.tetlet.2010.10.018

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A solution of potassium tert-butoxide in THF was shown to remarkably enhance the base-induced Sommelet-Hauser rearrangement of N-benzylic amino acid-derived ammonium ylides. (C) 2010 Elsevier Ltd. All rights reserved.

DOI： 10.1016/j.tet.2010.09.125

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：CHEMICAL SOC JAPAN  

The tether-assisted synthesis of [3]rotaxane by olefin metathesis is described. The bis(crown ether)s, in which two crown ethers are connected by a linker, were converted to tethered rotaxanes, followed by removal of the linkers to produce [3]rotaxane. The biscrown structures promoted the formation of the tethered rotaxane, resulting in a notable improvement in the yield of the [3]rotaxane.

DOI： 10.1246/cl.2010.24

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The tether-assisted synthesis of [3]rotaxane by olefin metathesis has been studied in detail. Bis(crown ether)s, in which two crown ethers are connected by a linker, were threaded onto ammonium salts bearing a terminal olefin to form pseudorotaxanes. The pseudorotaxanes were converted into tethered rotaxanes in the presence of Grubbs catalyst, followed by removal of the linkers to produce [3]rotaxanes in excellent yields. Preorganisation of the two reactive ends has led to a great improvement in the yield of [3]rotaxanes. The ring strain of the tethered rotaxanes and the flexibility of the pseudorotaxanes were responsible for the formation of the tethered rotaxanes.

DOI： 10.1080/10610278.2010.514611

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The synthesis of calix[4]arene-based molecular containers I and 2 along with the thermodynamic behaviors of cation binding are reported. The containers encapsulated N-methylpicolinium salts to form 1:1 host-guest complexes in chloroform. The thermodynamic investigations of the containers provide contrastive pictures for the process of their guest encapsulations. The encapsulation of I with the N-methylpicolinium cations, bearing a series of counter anions, was primarily enthalpy-driven. The enthalpic difference among the host-guest complexes of the salts was directly related to the total electrostatic stability of the ion-pairs. When 2 encapsulated a series of the N-methylpicolinium cations within its cavity, negative heat capacity changes were observed. This suggests that the changes in the solvation spheres of the container and its guest before and after the formation of the host-guest complex depend on temperature. (C) 2009 Elsevier Ltd. All rights reserved.

DOI： 10.1016/j.tet.2009.01.021

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：WILEY-V C H VERLAG GMBH  

DOI： 10.1002/chem.200902526

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Several models for the porphyrin ring current effect are constructed based on a classical line current approximation and their performances in reproducing the observed induced shifts of ligand protons in Sn(IV)(porphyrin) dicarboxylate complexes are compared. A new model is selected and it is found that the diamagnetic ring current running on the inner 16 pi-electron circuit of the porphyrin is the main contributor together with a minor paratropic ring Current oil the outer 20 pi-electron circuit. Conformational analyses of bis(biplienyl carboxylate) complexes of Sn(IV) (tetrapherylporphyrin) in solution were carried out with this porphyrin ring current effect model.

DOI： 10.3987/COM-08-11361

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A molecular container composed of monodeoxy-calix[4]arene and calix[4]arene is synthesized. The host binds planar cationic guests. The deoxy-aromatic ring acts as an open door when the guest is absent and closes on guest binding.

DOI： 10.1246/cl.2008.394

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Molecular tweezers 1b having two alkyl thiol chains were prepared. Intramolecular cyclization of the thiols under oxidative conditions afforded tweezers 2b containing a disulfide bond. X-ray crystal analysis and temperature dependent H-1 NMR spectra analysis revealed that the structure of 1b has a stepped anti arrangement of the three aromatic rings, although that of 2b adopted a cleft conformation because of the intramolecular interaction between the alkyl chain and the terminal naphthalene rings. The thioldisulfide redox reaction proceeded smoothly and reversibly to control the conformation of the tweezers. (c) 2007 Elsevier Ltd. All rights reserved.

DOI： 10.1016/j.tetlet.2007.11.056

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：TAYLOR & FRANCIS LTD  

Calix[5]arene-based artificial receptor 1 capped with chiral macrocycle 6 was synthesized and showed strong binding towards ethyltrimethylammonium derivatives via cation/pi and/or hydrogen bonding interactions. The calix[5]arene cavity provided the dissymmetric guest-binding environment in which chiral guests 9-19 were encapsulated in an enantioselective fashion. Thermodynamic studies for this chiral recognition gave an insight into the binding manner of the receptor: the enantioselective recognition is enthalpy favoured. Probably, the attractive interactions between the host and the guest gives rise to the enthalpy difference in enantioselection; however, the enthalpy gains of one of the enantiomers are compensated by entropy costs, reducing the enantioselectivity of the receptor.

DOI： 10.1080/10610270701742553

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Two new halogenated briarane diterpenes, (-)-2-deacetyljunceellin (1) and (-)-3-deacetyljunceellin (2), and five known diterpenoids, junceellin, praelolide, junceellolide A, B, and D were isolated from the Papuan gorgonian coral Junceella fragilis. The structures of the new metabolites were determined by extensive 2D NMR experiments and by chemical conversion. The absolute configuration of 2 was determined through the H-1 NMR study of the corresponding ester with a newly developed chiral auxiliary 3a.

DOI： 10.1246/bcsj.79.634

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A new simple model of porphyrin ring current effect was proposed based on a line current approximation. It can reproduce the porphyrin-induced shifts for several Sn(IV)(tpp) and Sn(IV)(oep) dicarboxylate complexes quite satisfactorily. Perpendicular arrangement of the aromatic rings in the diaromatic-carboxylate complexes of Sn(IV)(tpp) and Sn(IV)(oep) was clarified with this porphyrin ring current effect model. There are two structures, exo and endo, in solution in dinaphthalene-1- and 2- carboxylate complexes of Sn(IV)(tpp) and Sn(IV)(oep). The exo conformer is in dynamic equilibrium with the endo form in solution. Thermodynamic data of these conformational equilibria are given. © 2006 Elsevier Ltd. All rights reserved.

DOI： 10.1016/j.tet.2006.01.020

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new simple model of porphyrin ring current effect was proposed based on a line current approximation. It can reproduce the porphyrin-induced shifts for several Sn(IV)(tpp) and Sn(IV)(oep) dicarboxylate complexes quite satisfactorily. Perpendicular arrangement of the aromatic rings in the diaromatic-carboxylate complexes of Sn(TV)(tpp) and Sn(IV)(oep) was clarified with this porphyrin ring current effect model. There are two structures, exo and endo, in solution in dinaphthalene-1- and 2-carboxylate complexes of Sn(IV)(tpp) and Sn(IV)(oep). The exo conformer is in dynamic equilibrium with the endo form in solution. Thermodynamic data of these conformational equilibria are given. (c) 2006 Elsevier Ltd. All rights reserved.

DOI： 10.1016/j.tet.2006.01.020

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A new chiral carboxylic acid 1 was synthesized for determination of absolute configuration of secondary alcohols. Several chiral alcohols were converted to esters with 1. Their experimental esterification shift changes were successfully reproduced by the chemical shift simulation method combined with molecular dynamic simulation. (c) 2006 Elsevier Ltd. All rights reserved.

DOI： 10.1016/j.tetlet.2006.01.011

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Five new sulfur-containing polybrominated bisindole (1 similar to 5) were isolated from the red alga, Laurencia brongniartii, in addition to six related compounds (6 similar to 11), which have been previously found in the Okinawan alga. The structures of these new bisindole metabolites were elucidated on the basis of spectroscopic studies, as well as X-Ray crystallographic analysis of 1.

DOI： 10.3987/COM-05-10505

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The synthesis of new flexible molecular tweezers based on 3,4,8,10,11,13-hexahydro-1H,6H-2,5,9,12-tetraoxabenzo[1,2:4,5]dicyclooctene bearing two naphthalenes is presented. Intratnolecular CH/pi interaction between the alkyl ring and the two terminal naphthalenes controls the conformation to give a self-quenched cleft form. (c) 2005 Elsevier Ltd. All rights reserved.

DOI： 10.1016/j.tetlet.2005.08.016

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4-Thia-5 alpha- and 4-thia-5 beta-androstan-17-ones (1a and 1b) were synthesized in order to obtain the NMR shielding parameters for the thioether C-S bond. The complete NMR assignment of both the proton and carbon atoms for these compounds and substituent-induced shifts (SIS) from the corresponding androstanones (2a and 2b) are presented. A combination of the electric field effect and the anisotropy of the magnetic susceptibility of the C-S bond can successfully reproduced the observed SIS values for these androstanones. (c) 2005 Elsevier Ltd. All rights reserved.

DOI： 10.1016/j.tet.2005.02.015

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Conformational analysis of dinaphthalene-1-carboxylate complex of Sn-IV(tpp) (1) in solution was carried out using temperature dependent H-1 NMR spectra and chemical shift simulation method. It was found that two vertical conformers are in equilibrium in solution for 1.

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A new simple model of porphyrin ring current effect was proposed based on a line current approximation. It can reproduce the porphyrin-induced shifts for some Sn(IV)(tpp) dicarboxylate complexes quite satisfactorily. © 2004 Elsevier Ltd. All rights reserved.

DOI： 10.1016/j.tetlet.2004.12.028

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：PERGAMON-ELSEVIER SCIENCE LTD  

A new simple model of porphyrin ring current effect was proposed based on a line current approximation. It can reproduce the porphyrin-induced shifts for some Sn(IV)(tpp) dicarboxylate complexes quite satisfactorily. (C) 2004 Elsevier Ltd. All rights reserved.

DOI： 10.1016/j.tetlet.2004.12.028

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：Society of Synthetic Organic Chemistry  

Conformational analyses of flexible compounds with a chemical shift simulation method are described. It is known that NMR chemical shifts reflect the molecular structure, and hence, our method of analysis utilizes chemical shifts. Our newly developed chemical shift simulation method together with molecular dynamic calculation succeeded in the conformational analysis of the flexible compounds
cyclophanes, dicarboxylate complexes of Sn(IV) porphyrins and supramolecular complexes.

DOI： 10.5059/yukigoseikyokaishi.63.1080

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：PERGAMON-ELSEVIER SCIENCE LTD  

Synthesis of new flexible molecular tweezers 1.M-2 (M = 2H, Co, Zn, Cu, Ni) based on bis-dioxa[2.2]orthocyclophane bearing two porphyrins is presented. The molecular tweezers (1.(2H)(2)) can bind not only planar pi-electron acceptors, such as tetracyanoquinodimethane (TCNQ) and tetracyanobenzene (TCNB) but also a spherical guest C-60.

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：PERGAMON-ELSEVIER SCIENCE LTD  

4-Aza-5alpha-androstanone(1alpha) and 4-aza-5beta-androstanone(1beta) were synthesized in order to obtain the NMR shielding parameters for the secondary amine group. A combination of the electric field effect and the anisotropy of the magnetic susceptibility of the C-N bond can successfully reproduce the observed SIS values for these androstanes. Drastic chemical shift change of protons near-by nitrogen atom of ammonium salt was observed and shielding parameter for the secondary ammonium group was also obtained. (C) 2003 Elsevier Ltd. All rights reserved.

DOI： 10.1016/S0040-4039(03)01486-2

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：PERGAMON-ELSEVIER SCIENCE LTD  

[3]Catenane 5a and 5b were synthesized conveniently by olefin metathesis dimerization of pseudorotaxanes 3a and 3b. The yields of 5a and 5b were influenced by concentrations of 3a and 3b, and a ring size of a center wheel of [3]catenane. (C) 2003 Elsevier Ltd. All rights reserved.

DOI： 10.1016/S0040-4039(03)01424-2

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：PERGAMON-ELSEVIER SCIENCE LTD  

The synthesis and binding behavior of a Zn(II)-porphyrin having a calix[5]arene cap are presented. In order to synthesize such a bridged porphyrin, 5,15-bis(7-carboxy-1-naphthyl)-10,20-diphenylporphyrin having the syn arrangement of two naphthalene rings has been prepared. Amidation of the porphyrin and calix[5]arene having two amino functions and subsequent treatment of Zn(OAc)(2) gave a calix[5]arene capped Zn-porphyrin. Calix[5]arene-Zn-porphyrin was found to bind 4-methylpyridine much stronger than TPP-Zn. (C) 2002 Elsevier Science Ltd. All rights reserved.

DOI： 10.1016/S0040-4039(02)01655-6

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：PERGAMON-ELSEVIER SCIENCE LTD  

Structure elucidation of the inclusion complexes of monodeoxycalix[4]arene with small organic guests was carried out by X-ray crystallographic analysis and molecular dynamic simulation. Although the guest moves rapidly in the host cavity, the time averaged structure resembles the one obtained by the X-ray crystallography. Chemical shift simulation succeeded to reproduce the observed complexation induced shift. (C) 2001 Elsevier Science Ltd. All rights reserved.

DOI： 10.1016/S0040-4039(01)02062-7

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：PERGAMON-ELSEVIER SCIENCE LTD  

Dihydro-dibenzophenanthrene derivatives 1a (1b) were synthesised in order to obtain the NMR shielding parameters for naphthalene ring. The H-1 NMR assignment of 1a and substituent-induced shifts (SIS) from the corresponding androstanone ethylene ketal (2) are presented. A simple sum of the magnetic shielding of benzene rings can satisfactorily reproduced the observed SIS values due to the naphthalene ring of 1. (C) 2001 Elsevier Science Ltd. All rights reserved.

DOI： 10.1016/S0040-4039(00)02283-8

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：PERGAMON-ELSEVIER SCIENCE LTD  

Conformational analysis of 1,4,11,14-tetraoxa[4.4]metacyclophane was carried out using a combination of the molecular mechanics calculation, analysis of the temperature dependent H-1 NMR signal change and the chemical shift simulation method. The molecular mechanics calculation with Amber* force-field gave the two structures, one is highly symmetric C-2v and the other is C-i symmetric. The latter is identical to the structure found in the crystal. Both of the structures were confirmed by the chemical shift simulation. (C) 2000 Elsevier Science Ltd. All rights reserved.

DOI： 10.1016/S0040-4039(00)01876-1

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：PERGAMON-ELSEVIER SCIENCE LTD  

Thermodynamic parameters for the supramolecular complex formation of fullerene C-60 With calix[5]arene receptors are reported. The entropy change in chloroform is negative, but in toluene is positive, suggesting the tight solvation around the guest in toluene. Desolvation of the guest plays an important role in the supramolecular complex formation in toluene. (C) 2000 Elsevier Science Ltd. All rights reserved.

DOI： 10.1016/S0040-4039(99)02099-7

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Syntheses of the proposed structure of periplanone J (3) and its diastereomer (4), and the discussion on the true structure of PJ based on spectral analysis of 3,4 and the natural PJ are described.

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：AMER CHEMICAL SOC  

DOI： 10.1021/jo9810563

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：PERGAMON-ELSEVIER SCIENCE LTD  

Syntheses of the A-ring and the chiral C-ring model of taxol by using the intramolecular nitrile oxide cycloaddition and its diastereoselectivity based on MM2 transition state model are described. (C) 1997 Elsevier Science Ltd.

DOI： 10.1016/S0040-4039(97)00372-9

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Language：English   Publishing type：Research paper (scientific journal)  

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：LASER PAGES PUBL LTD  

The stereoselective synthesis of a taxol intermediate via a biomimetic route is described. Aldol condensation of gamma-butyrolactone and citral derivatives generated three stereogenic centers at positions C1, C2, and C11 corresponding to taxol. Intramolecular alkylation of the cyanohydrin ether efficiently formed the 12-membered ring system in which stereoselective reduction, followed by directed epoxidation, afforded the key intermediate epoxide.

DOI： 10.1002/ijch.199700006

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