Barton–Kellogg olefination of conjugated dithioxo compounds

Abstract

The first Barton–Kellogg olefination employing thioamides or thioureas as substrates is reported. Starting from the conjugated dithioxo compounds 1 and diazocompounds 2 we substituted the C˭S groups by ester substructures mono- (type 3) and obtained the disubstituted products 4. Using the same procedure, the tricyclic thiourea 5 was converted into a new ketene aminal 6. Intermediates such as primary cycloadducts or three-membered ring-contraction products could not be isolated for any reactions studied here.