Novel approach to the synthesis of enantioenriched sulfoxides. Highly diastereoselective alkylation of sulfenate anions with 1,4-asymmetric induction.

[reaction: see text] Efficient 1,4-asymmetric induction with an enantiopure aminoalkyl group as the chiral auxiliary has been achieved in the first example of diastereoselective alkylation (up to 98:2) of a sulfenate anion, readily prepared by oxidation of the corresponding thiolate. The stereochemistry of the sulfoxide produced is the opposite of that obtained by the conventional route based on oxidation of the sulfide precursor.

Highly stereoselective C-allylation of an enantiopure alpha-sulfinyl thioacetamide.

The alkylation of the lithium enolate of enantiopure alpha-cyclohexylsulfinyl thioacetamide 1 with allyl bromides 5 possessing an electron-withdrawing group at the vinylic position does not occur at the sulfur center - as expected in the sulfur series - but at the carbon center through conjugate addition followed by bromide elimination. The modest to excellent 1,2-asymmetric induction achieved by the alkylsulfinyl group (dr up to 100:0) is explained by an electronic model.