Reaction of silyl thioketones with lithium diethylphosphite: first observation of Thia–Brook rearrangement

Reaction of silyl thioketone 7 with lithium diethylphosphite at −98°C afforded a S-attack product 8 and formal C-attack products 10 and 11, which were formed by S-to-C migration of the phosphoryl group in the S-adduct followed by C-to-S migration of the silyl group (Thia–Brook rearrangement), in a ratio depending on the conditions. The relative facility of the Thia–Brook rearrangement was compared with that of the Brook rearrangement using the (t-butyldimethylsilyl)diphenylmethyl derivatives 22 and 23.