Erythrulose as a multifunctional chiron: Highly stereoselective boron aldol additions

We have investigated the formation of various metal enolates of 1-O-silylat ed erythrulose 3,4-acetonides. We were able to prepare boron enolates using Brown's dicyclohexylboron chloride/tertiary amine system. When these enola tes were allowed to react with a range of achiral aldehydes, highly stereos elective aldol additions took place with formation of the syn/syn stereoiso mer. This has been attributed to the exclusive formation of a Z boron enola te, which is in a sharp contrast with the usual behaviour of the aforementi oned reagent. (C) 1999 Elsevier Science Ltd. All rights reserved.