Chiral Sulfinyl Group Research Articles

有機硫黄官能基を有する不斉配位子を用いた触媒的不斉合成

Our recent results of catalytic asymmetric synthesis with chiral organosulfur ligands are reviewed. We have developed new chiral ligands with various coordinatable functionalities such as chiral sulfinyl, sulfenyl, phosphinyl, phosphinoamino, 1, 3-oxazoline, and imino groups, and applied them to Lewis acid- or transition metal-catalyzed asymmetric alkylations and cycloaddition reactions. The usefulness as chiral ligands in catalytic asymmetric alkylations and Diels-Alder reactions were demonstrated. The use of 2-phosphinophenyl and 2- (phosphi-noamino) phenyl 2-methoxy-1-naphthyl sulfoxide in palladium-catalyzed asymmetric alkylations provided high enantioselectivity (82 and 97%, respectively). 4- (1-Methoxyisopropyl) -2- [2- (2-methoxy- 1-naphthalenesulfinyl) phenyl] -1, 3-oxazoline was applied to MgI2-catalyzed Diels-Alder reactions as a chiral ligand, achieving high enantioselectivity (92%). Some of the structure of the intermediary metal complexes coordinated by the chiral ligands were determined by the X-ray crystallographic analysis. The mechanisms of the asymmetric synthesis with the ligands are proposed on the basis of the structure of the intermediary complexes and the stereo-chemical results obtained.

New chiral sulfoxide ligands in catalytic asymmetric Diels–Alder reactions: double acceleration by the chiralities of the sulfoxides and oxazolines

New chiral sulfoxide ligands which are useful for catalytic asymmetric Diels–Alder reactions have been developed. The new ligands involve a chiral sulfinyl function and a 1,3-oxazoline ring with an asymmetric carbon center, in which the chiral sulfinyl group has been revealed to play a crucial role in achieving high enantioselectivity in asymmetric Diels–Alder reactions. Among the Lewis acid catalysts employed, magnesium iodide provided the highest chemical and stereochemical efficiency in the cycloaddition reactions. A mechanistic pathway for the asymmetric synthesis is proposed on the basis of the stereochemical outcomes obtained.

Palladium-catalyzed allylic nucleophilic substitution reactions of ( E)-γ-acetoxy-α,β-unsaturated p-tolylsulfoxides

Regio- and diastereoselective nucleophilic allylic substitutions of optically pure ( E)-γ-acetoxy-α,β-unsaturated p-tolylsulfoxides 2 and 3 with sodium dimethyl malonate have been carried out. The reactivity of these substrates is controlled by both the chiral sulfinyl group and the size of the alkyl group attached at the γ-terminus of the allylic system. This process constitutes an example of palladium-mediated resolution of a 1:1 mixture of acetates 2 and 3.

Palladium-catalyzed asymmetric reactions enantiocontrolled by chiral organosulfur functionality

Participation of chiral sulfinyl functionality in palladium-catalyzed asymmetric reactions is demonstrated by using chiral sulfoxides as chiral ligands or chiral substrates. New chiral ligands, o-(phosphinoamino)phenyl and o-phosphinophenyl sulfoxides, have been developed. The structure of an intermediary palladium complex was determined by X-ray crystallographic analysis. The palladium-catalyzed asymmetric 1,3-rearrangements of (1,3-butadienyl)cyclopropanes bearing chiral sulfinyl groups to cyclopentenes are described. The participation of the chiral sulfinyl group to the palladium catalyst is described.

Synthesis of Highly Optically Active Polysulfoxides by Asymmetric Oxidation of Polysulfides

Novel highly optically active polysulfoxides having chiral sulfinyl groups in the main chain were prepared by asymmetric oxidation of the corresponding polysulfides by using chiral N-sulfonyloxaziridine (6). The polysulfoxide with the enantiomeric excess up to 91% ee was obtained in good chemoselectivity when the reaction was carried out with 1 equiv of (−)-N-sulfonyloxaziridine, (−)-6, in chloroform at room temperature followed by reflux. The enantiomeric excess was estimated from the 13C NMR spectrum, and the stereochemistry at the sulfur atom was speculated by comparison of CD spectra of the polysulfoxides with that of the model compound ((S)-p-tolyl methyl sulfoxide). This asymmetric oxidation is the first example of introduction of chirality in good enantioselectivity into the main chain of a polymer by polymer reaction, that is, the first example of the control of “tacticity” by polymer reaction. In fact, the shift of the glass transition temperature of the polysulfoxide was observed depending on the change of tacticity of the polymer. The obtained polymer is regarded as one of the first examples of the polymers having heteroatom chirality in the main chain.

ChemInform Abstract: Studies on Novel and Chiral 1,4‐Dihydropyridines. Part 6. Preparation of a Polymer‐Supported 1,4‐Dihydropyridine Having a Chiral Sulfinyl Group and Its Application to Biomimetic Reduction.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

1,6-Asymmetric Induction by Reductive Acetal Cleavage of a Bicyclic Acetal Using a Sulfinyl Chiral Auxiliary.

A new synthetic route to a chiral 2, 5-disubstituted tetrahydropyran has been achieved by asymmetric reductive acetal cleavage of a bicyclic acetal having a chiral sulfinyl group as a chiral auxiliary. It was found that the (5S)-tetrahydropyran was obtained preferentially (up to 96 : 4) with an R-sulfinyl chiral auxiliary by an efficient 1, 6-asymmetric induction from sulfinyl chirality to the prochiral center on the bicyclic ring.

Studies on Novel and Chiral 1,4-Dihydropyridines. VI. Preparation of a Polymer-supported 1,4-Dihydropyridine Having a Chiral Sulfinyl Group and Its Application to Biomimetic Reduction

Studies on Novel and Chiral 1,4-Dihydropyridines. VI. Preparation of a Polymer-supported 1,4-Dihydropyridine Having a Chiral Sulfinyl Group and Its Application to Biomimetic Reduction

Remote Asymmetric Induction in Lewis Acid-Catalyzed Diels-Alder Reaction of .ALPHA.,.BETA.-Unsaturated Enones Having a Chiral Sulfinyl-Substituted, 5-Membered Aromatic Heterocycle.

Two types of chiral sulfoxides as Diels-Alder dienophiles were synthesized and high levels of diastereoselectivity were observed in cycloadditions. 2-Furyl and 2-thienyl α, β-enones, bearing a chiral sulfinyl group in the heterocycle, served as efficient dienophiles in Diels-Alder reactions, where the catalytic use of aluminium chloride or a lanthanide triflate effected the cycloaddition with cyclopentadiene affording the endo adduct with high diastereoselectivity, ranging from 91% to 98%.

1,6-Asymmetric Induction Utilizing Asymmetric Desymmetrization by Diastereoselective C-O Bond Fission of the 4-Substituted Bicyclic Acetal: Application to a Synthesis of (-)-Frontalin.

1,6-Asymmetric induction was achieved in the acid-induced diastereoselective acetal cleavage reaction of a 4-substituted bicyclic acetal 8 bearing a chiral sulfinyl group. On treatment with titanium tetrachloride and 2,6-disubstituted pyridine bases, 8 gave a synthetically versatile 3,3-disubstituted dihydropyran derivative 9a with moderate diastereoselectivity. The utility of this chiral synthon was successfully demonstrated by a formal synthesis of (-)-frontalin.

ChemInform Abstract: Studies on Novel and Chiral 1,4‐Dihydropyridines. Part 5. Hantzsch‐ Type 1,4‐Dihydropyridines Having a Chiral Sulfinyl Group: Syntheses, Structures, and Biological Activity as a Calcium Channel Antagonist.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

ChemInform Abstract: Effect of the Neighboring Oxygenated Substituent on Asymmetric Reduction with Hantzsch‐Type 1,4‐Dihydropyridines Having a Chiral Sulfinyl Group.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

Studies on novel and chiral 1,4-dihydropyridines. V. Hantzsch-type 1,4-dihydropyridines having a chiral sulfinyl group: Syntheses, structures, and biological activity as a calcium channel antagonist

Abstract 4-Aryl and 4-methyl substituted Hantzsch-type 1,4-dihydropyridines having a chiral sulfinyl group as an electron-withdrawing group were successfully synthesized in an optically active form from β-ketosulfoxides via two routes. The relationship between calcium channel antagonist activity and the structures of 4-aryl derivatives was also studied.

Studies on Chiral Organosulfur Compounds. VI. The Use of a Chiral Diene Bearing an Optically Active Sulfinylmethyl Group in the Lewis Acid-Catalyzed Intramolecular Asymmetric Hetero Diels-Alder Reaction.

An asymmetric Diels-Alder reaction with a diene bearing a chiral sulfinyl group is described. The Lewis acid-catalyzed intramolecular asymmetric hetero Diels-Alder reaction of a chiral α'-sulfinyl-α, β-unsaturated ketone derived from 3-methylcitronellal produced optically active 4a, 5, 6, 7, 8, 8a-hexahydro-1H-2-benzopyran derivatives. On the basis of the stereochemical results obtained, a plausible mechanism for the asymmetric induction is presented.

Effect of the neighbouring oxygenated substituent on asymmetric reduction with Hantzsch-type 1,4-dihydropyridines having a chiral sulfinyl group

Introduction of the oxygen substitutent at C-6 of the Hantzsch-type compound having a sulfinyl group at C-5 affects the reduction of ketones with respect to both reactivity and stereoselectivity.

Stereochemistry of highly selective transition metal or Lewis acid-catalyzed asymmetric reactions

Recent progress of our studies on catalytic asymmetric synthesis is reviewed focused on transition metal-catalyzed intramolecular asymmetric reactions using chiral organo-sulfur groups as main chiral auxiliaries such as asymmetric vinyl-cyclopropane-cyclopentene rearrangements and intramolecular asymmetric metallo-ene reactions, Lewis acid-catalyzed intramolecular asymmetric ene reactions with chiral sulfinyl groups, and palladium-catalyzed intramolecular asymmetric allylations via chiral enamines.

A novel asymmetric desymmetrisation of meso-cyclopentane-1,2-diol via diasteroselective β-elimination of chiral α-arylsulfinyl acetals

meso-Cyclopentane-1,2-diol was differentiated via diasteroselective C–O bond fission of the acetal utilising the anion stabilised by a neighbouring chiral sulfinyl group to provide the chiral alcohol.

ChemInform Abstract: Asymmetric Synthesis of Biologically Active Compounds Bearing a Chiral Sulfinyl Group

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

The reaction of nitrones with (R)-(+)-methyl p-tolyl sulfoxide anion; asymmetric synthesis of optically active secondary amines

Optically active α-substituted N-hydroxylamines have been prepared by the addition of (R)-(+)-and (S)-(−)-methyl p-tolyl sulfoxide anions to nitrones highly efficiently. This method is applicable to the synthesis of optically active N-hydroxy tetrahydroisoquinoline derivatives 6a–6e, which are important precursors of various isoquinoline alkaloids such as (R)-(+)-salsolidine. (8). Furthermore, the reaction of nitrones bearing chiral sulfinyl group with organometallic reagents provides an efficient method for induction of asymmetric quaternary carbon α to nitrogen of secondary amines.

Asymmetric Synthesis of Biologically Active Compounds Bearing a Chiral Sulfinyl Group

Abstract The asymmetric synthesis of (R C,SS) and (S C,R S), important intermediates in the synthesis of optically pure Sparsomycin analogs, is discussed. The enantioselective synthesis of both isomers, R and S, of Oxisuran and three of their bioisosters is also described. In both strategies o.p. methanesulfinate esters of DAG were used as starting material.