Chiral Sulfinyl Research Articles

Stereochemistry of transition metal catalyzed asymmetric intramolecular allyl transfer in chiral α-sulfinyl allylic esters

The stereochemistry of palladium or nickel catalyzed asymmetric intramolecular allyl transfer in chiral α-sulfinyl allylic esters was determined. The participation of the catalyst and the chiral sulfinyl functionality in these transformations, presumably by the coordination of the sulfinyl group to the catalyst, is discussed, and a novel mechanism is proposed for the rationalization of the results obtained.

Transition metal-catalyzed asymmetric cycloaddition reactions of a chiral (β-sulfinyl)vinylcyclopropane derivative: asymmetric synthesis of a cyclopentane derivative using a chiral sulfinyl functionality as the chiral source

Asymmetric synthesis of a cyclopentane derivative using a chiral sulfinyl functionality as the chiral source has been successfully executed by a transition metal-catalyzed asymmetric cycloaddition reaction of a chiral (β-sulfinyl)vinylcyclopropane derivative with acrylonitrile. The effects of the catalysts, ligands, and solvent were examined. The degree of the asymmetric induction and the chemical yield were highly dependent on the catalyst and, especially, the ligand used. A plausible mechanism of the asymmetric induction is proposed.

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: Participation of the Chiral Sulfinyl Functionality in Palladium‐Catalyzed Asymmetric Vinylcyclopropane—Cyclopentene Rearrangements.

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: 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.

Participation of the chiral sulfinyl functionality in palladium-catalyzed asymmetric vinylcyclopropane-cyclopentene rearrangements

Stereochemical studies on the palladium-catalyzed asymmetric 1, 3-rearrangements of [4-chiral arylsulfinyl-1, 3( E or Z)-butadienyl]cyclopropanes to chiral cyclopentenes are described. The plausible mechanism for the rationalization of the stereochemical outcomes is proposed. [Display omitted]

Synthesis and Structural Investigations of Novel Palladium(II) and Rhodium(I) Complexes Containing Chiral Ligands with a Stereogenic Sulfur Donor, Such As β-Amino Sulfoxides and C2-Symmetric Bis-Sulfoxides1

Two kinds of new optically active chelating ligands bearing a chiral sulfinyl functionality, namely the 3,4-bis-(p-tolylsulfinyl)hexanes 4 and the N-mono- and N,N-disubstituted β-p-tolylsulfinyl ethylamines 5 and 2, have been synthesized and their coordination chemistry with Pd(II) and Rh(I) metals has been studied in detail. Complexes formed with ligands 4 featured a homocoordination between the two sulfur donors and the metal atom, in solution as well as in the solid state, as demonstrated by X-ray diffraction of cis-dichloro[3,4-bis-(p-tolylsulfinyl)hexane]palladium(II) ((3R,4R,RS,RS)-7), in which the ligand shows a C2 symmetry. Complexes formed with ligands 2 and 5 showed a heterocoordination of the metal by the sulfur and the nitrogen donors, as confirmed by X-ray diffraction of cis-dichloro[N,N-dimethyl-2-(p-tolylsulfinyl)ethylamine]palladium(II) ((R)-6). All nine complexes 6−11, displaying a monomeric structure, have been synthesized and completely characterized in the solid state (IR, MS-FAB) as w...

Chiral sulfoxide ligands bearing nitrogen atoms as stereocontrollable coordinating elements in palladium-catalyzed asymmetric allylic alkylations

Palladium-catalyzed asymmetric allylic alkylations were studied by using chiral sulfoxide ligands bearing nitrogen atoms as coordinating elements, such as chiral α-sulfinylacetamides, β or γ-amino sulfoxides, and β-sulfinyl sulfonamides. The effects of the chiral sulfinyl functions on the asymmetric induction were demonstrated. Use of ( S)-2-pyrrolidinophenyl p-tolyl sulfoxide or ( S)-2-( N-butyl- N-methylaminomethyl)phenyl p-tolyl sulfoxide as chiral ligands in the palladium-catalyzed asymmetric allylic alkylations provided the highest enantioselectivity (50 or 58% e.e., respectively) among chiral sulfoxide ligands examined by us. The participation of the sulfinyl groups in these catalytic asymmetric reactions is rationalized, and the mechanism for the asymmetric induction is proposed on the basis of the stereochemical outcome obtained.

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.

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

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.

General Method for Asymmetric Synthesis of alpha-Methylsulfinyl Ketones: Application to the Synthesis of Optically Pure Oxisuran and Bioisosteres.

The first asymmetric synthesis of oxisuran [1, (methylsulfinyl)methyl 2-pyridyl ketone], a synthetic immunosuppressive drug, is described. Both enantiomers were efficiently synthesized, in optically pure form, using DAG methodology for the key condensation step. Attempts to couple metal enolates of aryl methyl ketones with chiral sulfinyl compounds led to some epimerization at sulfur. This loss of chirality was circumvented by reacting the alpha-lithio derivatives of the N,N-dimethylhydrazones derived from these ketones with either the (R)- or the (S)-methanesulfinate of diacetone D-glucose, to yield the corresponding alpha-(methylsulfinyl)methylhydrazones, with complete inversion of chirality at sulfur. Hydrolysis of the resulting hydrazones with copper(II) chloride gave 1 in optically pure form. The generality of the method was demonstrated by the preparation of the optically active oxisuran analogs, 2-4, in which the pyridyl moiety was replaced by phenyl, furyl, and thienyl moieties, respectively. The optical purities of these products were determined by proton NMR spectroscopy, using chiral shift reagents, following conditions established by the study of racemic mixtures of the beta-keto sulfoxides.

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.

ChemInform Abstract: Asymmetric Synthesis of Chiral Sulfinyl Derivatives Using (‐)‐Menthyl 4‐Bromobenzenesulfinate.

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.