Abstract: Lithiated silylthioacetals 1 react with w-bromoalkyl isocyanates 2 via addition to the isocyanate, a 1, 3-silyl shift and ringclosure by bromide displacement to give lactams 6. The latent aoxo group can be liberated by thioacetal cleavage with hypervalent iodine to yield diones 10. Key words: silyl-stabilized carbanions, w-bromoisocyanates, thioacetals, hypervalent iodine
