Recent developments in chiral non-racemic sulfinyl group chemistry in asymmetric synthesis

Abstract

Chiral sulfinyl groups have been widely used in organic synthesis as a stereo-and enantiodirecting functionality and the high efficiency of the selectivity has received much attention in recent years. In this review we wish to cover the work published in the literature since 1996. The participation of a chiral sulfinyl function in a wide range of reactions as well as the application of these methodologies to the synthesis of natural products are reported.

Asymmetric Diels−Alder Reactions of a New Enantiomerically Pure Sulfinylquinone: A Straightforward Access to Functionalized Wieland−Miescher Ketone Analogues with (R) Absolute Configuration

“…The same π-facial diastereoselectivity observed in cycloadditions under thermal or Lewis acid conditions suggested the existence of a similar reactive conformation of the sulfinyl quinonic system in all the cases. This was in sharp contrast with the previously described results obtained with 2-substituted 3-sulfinylquinones lacking the methoxy group at C-5 position which afforded cycloadducts with opposite absolute configuration when the reaction was performed under thermal conditions or in the presence of chelating Lewis acid. ,,, A detailed examination of the three possible situations (Figure ) allowed us to propose that, under Lewis acid conditions and assuming preferred chelation with ZnBr 2 , 2B could be the reactive conformation responsible of the favored approach of dienes from the less hindered top face of ( S S )- 2 to afford cycloadducts with the ( R ) absolute configuration at the angular methyl group.

7 Expected major conformations of ( S S )- 2 in the presence of 1 equiv of Lewis acid.

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“…The use of sulfinyl benzoquinones as dienophiles for Diels−Alder reactions has experienced increased interest in recent years. , This methodology found its first synthetic application in the enantioselective synthesis of angucyclinones using an enantiomerically pure sulfinyl naphthaquinone as dienophile …”

“…1971, 10, 496. ( The use of sulfinyl benzoquinones as dienophiles for Diels-Alder reactions has experienced increased interest in recent years. 6,7 This methodology found its first synthetic application in the enantioselective synthesis of angucyclinones using an enantiomerically pure sulfinyl naphthaquinone as dienophile. 8 Further investigations allowed the construction of enantiomerically pure angucyclinone-type skeletons via a tandem cycloaddition/pyrolytic sulfoxide elimination sequence with kinetic resolution of the racemic semicyclic dienes.…”

Stereoselectivity Switch in the Trapping of Polar Organometallics with Andersen’s Reagent—Access to Highly Stereoenriched Transformable Biphenyls

“…Either way, in our study (Scheme b) as well as in Clayden’s and Knochel’s, the trapping of the biaryllithium furnished in all cases a ca. 1:1 mixture of diastereomers. , In fact, the trapping of configurationally stable, chiral racemic, polar carbometalated species with Andersen’s reagent seems to proceed with a very low level of resolution in all cases, regardless of the nature of the chirality element (central, axial, planar) on the nucleophile used (Scheme a), − which contrasts with the otherwise usually excellent stereoinduction achieved with the sulfinyl group . In the present paper, we describe the unusual kinetic resolution of biphenyls by means of Andersen’s reagent upon treatment of 2-iodobiphenyls with isopropylmagnesium chloride (Scheme c).…”

New Insights into the Synthesis and Biological Activity of the Pamamycin Macrodiolides

“…Common intermediate 29 was accessible using enantiomerically pure sulfoxide 30 as chiral auxiliary. [14] Synthesis of the common intermediate 29 started with the β-ketosulfoxide 31 obtained from ethyl butyryl acetate (32) after formation of the dioxolane and a Claisen-type condensation with the anion of (-)-(S)-methyl-p-tolylsulfoxide (30, Scheme 6). [15] DIBAL-H reduction and subsequent hydrolysis afforded the corresponding [S(S),2(R)]-β-hydroxysulfoxide 33 in 80% yield (de > 95%) which was subjected to an Evans reduction [16] giving anti-[S(S),2(R),4(S)]-β,δ-dihydroxy-sulfoxide 34 (de>95%), in 97% yield by crystallization.…”