The diastereoselective Meth-Cohn epoxidation of camphor-derived vinyl sulfones

Some camphor-derived vinyl sulfones bearing an oxygen functionality at the allylic position have been synthesised and their nucleophilic epoxidation reactions under Meth-Cohn conditions have been explored. The γ-oxygenated camphor-derived vinyl sulfones underwent mildly diastereoselective nucleophilic epoxidation reactions, affording the derived sulfonyloxiranes in up to 5.8:1 dr. The diastereoselectivities observed were sensitive to the reaction conditions employed. In contrast, no stereoselectivity was observed in the nucleophilic epoxidation of the corresponding γ-oxygenated isobornyl vinyl sulfone. A tentative mechanism has been proposed to explain the origins of the diastereoselectivity.

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(1S,4R)-1-({[(1′E)-3′-Hydroxyprop-1′-enyl]sulfonyl}methyl)-7,7-dimethylbicyclo[2.2.1]heptan-2-oneC13H20O4SEe = 100%[α]D26=+26.8 (c 0.5, MeOH)Source of chirality: homochiral templateAbsolute configuration: (1S,4R)

(1S,4R)-1-({[(1′E)-3′-Benzyloxyprop-1′-enyl]sulfonyl}methyl)-7,7-dimethylbicyclo[2.2.1]heptan-2-oneC20H26O4SEe = 100%[α]D26=+27.3 (c 0.57, MeOH)Source of chirality: homochiral templateAbsolute configuration: (1S,4R)

(1S,2R,4R)-1-({[(1′E)-3′-Benzyloxyprop-1′-enyl]sulfonyl}methyl)-7,7-dimethylbicyclo[2.2.1]heptan-2-olC20H28O4SEe = 100%[α]D25=-23.7 (c 0.7, MeOH)Source of chirality: homochiral templateAbsolute configuration: (1S,2R,4R)

(1S,2R,4R)-1-({[3′-Benzyloxypropyl]sulfonyl}methyl)-7,7-dimethylbicyclo[2.2.1]heptan-2-olC20H30O4SEe = 100%[α]D25=-20.0 (c 0.13, MeOH)Source of chirality: homochiral templateAbsolute configuration: (1S,2R,4R)