Easy transformations of vinyl N,N-diisopropyl carbamates into silyl enol ethers or aldehydes by addition of methyllithium

Homoaldols and 4-hydroxy silyl enol ethers have been prepared upon addition of methyllithium to 4-hydroxyvinyl N,N-diisopropyl carbamates obtained fro m Hoppe's homoaldolisation reaction followed by addition, in presence of an excess of HMPA, of water or tert-butyldimethylsilyl chloride, respectively . In the case of silyl enol ethers, a total retention of the Z configuratio n of the double bond was observed. This simple procedure allows an easy pre paration of gamma-lactones from the homoaldol adducts. (C) 1999 Published b y Elsevier Science Ltd. All rights reserved.