| An approach toward the total synthesis of the macrocyle FK-506 is described. The convergent strategy divides the macrocycle into four subunits. Improvements in the synthesis of subunits C27--C34 and C 11--C21 are described. The coupling strategies of the top segment C8--C21, and the bottom segment C 22--C34 are discussed.; The synthesis of C11--C21 described involves a substrate controlled anti-aldol and approaches to selectively form the E-C19--C20 double bond and regioselectively reduce a gamma,delta-double bond over an alpha,beta-double bond and a remote tri-substituted double bond are discussed. |
