A new synthesis of castasterone and brassinolide from stigmasterol. A concise and stereoselective elaboration of the side chain from a C-22 aldehyde
作者:Thomas G. Back、Peter G. Blazecka、M. Vijaya Krishna
DOI:10.1139/v93-022
日期:1993.2.1
Brassinolide (1) and castasterone (2) were prepared from aldehyde 7, in turn available from stigmasterol (3). The addition of (E)-1-propenyllithium to 7, followed by diastereoselective Sharpless epoxidation of allylic alcohol 8 using (L)-(+)-diethyl tartrate, and regioselective epoxide-opening of (threo) epoxy alcohol 15 with isopropylmagnesium chloride in the presence of a catalytic amount of cuprous