- Lewis acid/base catalyzed [2+2]-cycloaddition of sulfenes and aldehydes: A versatile entry to chiral sulfonyl and sulfinyl derivatives
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The first catalytic asymmetric synthesis of β-sultones is reported. This development has enabled a rapid access to a number of highly enantioenriched biologically interesting sulfonyl and sulfinyl compound classes, which makes use of the inherent ring strain of the four-membered heterocycles. The products possess either two vicinal stereocenters, such as in β-hydroxy-sulfonamides, -sulfonates, -sulfones, -sulfonic acids, -sulfinic acids, γ-sultines, and γ-sultones or a single stereocenter, such as in α-branched alkyl or allyl sulfonic acids. This work also represents the first application of sulfene intermediates in asymmetric catalysis. The reactivity of a sulfene normally acting as an electrophile could be reverted by the formation of a nucleophilic zwitterionic sulfene-amine adduct. To achieve a combination of high enantioselectivity and reactivity, cooperative catalytic action of a chiral nucleophilic tertiary amine (the cinchona alkaloid derivative diydroquinine 2,5-diphenyl-4,6-pyrimidinediyl diether ((DHQ)2PYR)) and Bi(OTf)3 or In(OTf)3 was of primary importance.
- Koch, Florian M.,Peters, Rene
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- Rapid asymmetric access to β-hydroxysulfinic acids and allylsulfonic acids by chemoselective reduction of β-sultones
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The reduction of readily available optically active β-sul-tones bearing a β-trichloromethyl substituent proceeds chemoselec-tively at three different sites via C-Cl, C-O or S-O bond cleavage and allows for the formation of highly enantioenriched β-hydroxy-sulfinic acids and allylsulfonic acids.
- Koch, Florian M.,Peters, René
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experimental part
p. 1505 - 1509
(2009/04/07)
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