作者:Andrew S. Thompson、David M. Tschaen、Pamela Simpson、Donna J. McSwine、Robert A. Reamer、Thomas R. Verhoeven、Ichiro Shinkai
DOI:10.1021/jo00052a013
日期:1992.12
The synthesis of PAF antagonist MK-287 is described. Our route utilizes a 5-aryl-substituted butyrolactone as the key optically active intermediate, which is constructed in four steps from commercially available 5-iodovanillin. Asymmetry is introduced using beta-chlorodiisopinocampheylborane to reduce a prochiral ketone. The second asymmetric center is installed relative to the existing stereocenter with stereocontrol exceeding 50:1. This step utilizes a copper-catalyzed Grignard displacement of an alpha-bromo ether. The alpha-bromo ether was generated using trimethylsilyl bromide activation of a silylated hemiacetal. The details leading to our development of the silyl acetal method for anomeric activation are also described.