Total synthesis of natural (+)-hyacinthacine A(6) and non-natural (+)-7a-epi-hyacinthacine A(1) and (+)-5,7a-diepi-hyacinthacine A(6)

摘要

Naturally occurring (1S,2R,3R,5R,7aR)-1,2-dihydroxy-3-hydroxymethyl-5-methylpyrrolizidine [(+)-hyacinthacine A(6), 2] together with unnatural (1S,2R,3R,7aS)-1,2-dihydroxy-3-hydroxy-methylpyrrolizidine [(+)-7a-epi-hyacinthacine A(1), 3] and (1S,2R,3R,5S,7aS)-1,2-dihydroxy-3-hydroxy-methyl-5-methylpyrrolizidine [(+)-5,7a-diepi-hyacinthacine A(6), 4] have been synthesized from a DALDP derivative [5, (2R,35,4R,5R)-3,4-dibenzyloxy-2'-O-tert-butyldiphenylsilyl-2,5-bis(hydro xymethyl)-pyrrolidine], as the homochiral starting material. The synthetic process employed took advantages of Wittig methodology followed by internal lactamization, in the case of (+)-7a-epi-hyacinthacine A(1) (3), and reductive amination for (+)-hyacinthacine A(6) (2) and (+)-5,7a-diepi-hyacinthacine A(6) (4).