Atroposelectivity of reactions of benzylic metalated thiobenzamides and thionaphthamides

N,N-Dialkyl-2-methylbenzenecarbothioamides and naphthalenecarbothioamides were prepared by thionation of amides with Lawesson's reagent under unusual conditions. Their axial chirality was evidenced. Benzylic deprotonation of thioamides bearing N,N-diisopropyl groups with sec-butyllithium was selective. The resulting anions were reacted with prochiral electrophiles (aromatic aldehydes, an unsaturated aldehyde or ketone, and an imine) to afford diastereomeric adducts (up to 88:12 dr). This is the first report on atropo-selective C-C bond formation in the benzylic position of thioamides. (C) Wiley-VCH Verlag GmbH Co.