| Abstract: | Starting from the benzylidene lactone 3 of D-(−)-quinic acid the cyclohexyl fragment 15 (C-28-C-34 part) of the immunosuppressant FK506 was synthesized. Key steps include homolytic deoxygenation reactions on compounds 4 and 6 as well as a regioselective opening of the benzylidene acetal 5 . Opening of the lactone 7 to provide the methyl ester 8 was followed by methylation of the hydroxy group to give 9 . Further steps provided the aldehyde 12 which was elongated to the alkyne 15 . This sequence provides 15 in gram quantities. |
