[摘要]：such as brasilinolide A is prepd. convergently using the 1,5-anti distereoselective aldol addn. reactions of dicyclohexylboron enolates derived from Me ketones with nonracemic aldehydes as the key steps. I is assembled from nonracemic oxooctenoate II (prepd. in four steps from nonracemic 2-allyloxirane and lithium acetylide ethylenediamine complex), siloxydibenzyloxyhexanone III (prepd. in three steps from 5-(tert-butyldimethylsiloxy)-1-pentene and acetonyltriphenylphosphorane), and either methylhexenal IV (prepd. in three steps from a nonracemic pseudoephedrine amide and 4-iodo-1-butene) or siloxypentanal V (prepd. in four steps from a nonracemic propanoyloxazolidinone and acrylonitrile). The order of reaction of dicyclohexylboron enolates derived from II or III with nonracemic aldehydes in the prepn. of I can be changed.
