Christian Maignan

Un dienophile chiral tres reactif : le Z-(R)S p-tolylsulfinyl-3 propenoate de methyle

Abstract Methyl Z-(R)S 3-p-tolylsulfinyl propenoate reacts under mild conditions with cyclopentadiene. A high stereoselectivity and diastereospecificity were observed. The structure and absolute stereochemistry were established by N.M.R.

An easy synthesis of chiral sulfinyl allylic bromides and their use in the preparation of(R)S- and (S)S-2-p-tolylsulfinyl-1,3-alkadienes

Abstract Condensation of (R)-vinyl-p-tolylsulfoxide anion on carbonyl compounds led directly to chiral allylic sulfinylalcohols 1 . By treatment with NBS/Me 2 S, these alcohols 1 were converted into the rearranged primary allylic bromides 2 via SN 2 ′ displacement. Optically pure (R)- and (S)-2-p-tolylsulfinyl-1,3-alkadienes 3 resulted from the action of KOH/ROH upon these bromides 2 via E 2 ′ eliminations.

Asymmetric intermolecular Diels-Alder reactions of enantiopure sulfinyl-homo- and -hetero-dienes : preliminary results

Abstract Reaction of (E)-(+)-(R)-2-p-tolylsulfinyl-1,3-pentadiene 1 with maleimide afforded 3 as a single, enantiomerically pure adduct under very mild conditions. 3 resulted from exclusive endo approach by a completely diastereofacialselective route. On the other hand, heterodiene (+)-(S)-3-p-tolylsulfinyl-3-buten-2-one 2 smoothly reacted with sensitive 2-methylenetetrahydrofuran yielding 1:1 diastereomeric dioxaspiroadducts 4a and 4b, readily separated by liquid chromatography.

Un synthon céténique chiral masque, le (R)S ethynyl p-tolylsulfoxyde

Abstract A new chiral masked ketene synthon, R-(+)-ethynyl p -tolylsulfoxide reacts with cyclopentadiene to give two separable diastereoisomers. Both were transformed very easily in (+)-(1R, 4R) and (−)-(1S, 4S) dehydronorcamphor.

Acces aux (R)S acyl-1 vinyl p-tolylsulfoxydes a partir du (R)S dimethylamino-2 p-tolylsulfinyl-1 ethane. Leurs reactivites en tant que dienophile.

An efficient sequence is described whose key step involves an Hofmann elimination of (R)S 2-dimethylamino-1 p-tolylsulfinyl ethane to obtain chiral (R)S 1-acyl-vinyl p-tolylsulfoxides. Reactivity and stereoselectivity are discussed in the Diels-Alder reaction.

First syntheses of chiral 2-sulfinylbutadienes

Abstract The title compounds were readily prepared respectively from (S)-3-p-tolylsulfinylbut-3-en-2-ol 3 and (S)-3-p-tolylsulfinylbut-3-en-2-one 4.

(S)-(+)-3-p-Tolylsulfinylbut-3-en-2-one: A spectacular oxabutadiene for asymmetric cycloaddition of styrenic compounds

Abstract Heterocycloaddition of optically active (S)-(+)-3-p-tolylsulfinylbut-3-en-2-one 1 was successfully achieved with various electron-rich dienophiles in extremely mild and non-catalytic conditions. Nature of the dienophile (enol ether 2 v.s. styrene 3 ) proved to play a critical role in the stereochemical outcome of the reaction: less than 14% de with 2 , more than 94% de with 3 .

Preparation of optically active 2-(or 3)(p-tolylsulfinyl)-3(or 2)furyl- or thienylcarboxaldehydes

Abstract The preparation of the four enantiomerically pure title compounds is described by reaction of (1)-(−)-Ss-menthyl-p-toluenesulfinate on furan or thiophene precursors.

Syntheses of enantiomerically pure furyl and thienyl p-tolyl sulfoxides

Abstract We report a highly enantioselective reaction of Grignard reagents, derived from simple furans or thiophene, with (−)-(S)-menthylsulfinate to give in high yield enantiomerically pure furyl and thienylsulfoxides.

The dimethyl(1-phenylthio)cyclopropylsilyl group as a masked hydroxyl group

Abstract The title group has been used as a masked hydroxyl group, allowing a mild and high yielding oxidation of the CSi bond. Its use in various transformations demonstrates its chemical stability as well as its ability to be transformed into the corresponding OH group even in the presence of sensitive functionalities.