Alkyne zip reaction in the synthesis of a taxoid C-ring

International audienceHydrazone 30, precursor of a taxoid C-ring, was synthesized in 7 steps from commercial 2-methyl-1,3-cyclohexanedione. An enantioselective approach to 30 was also investigated, using a reduction of diketone 11 with bakers' yeast to introduce enantioselectivity. During the alkyne isomerization step, anionic cyclizations of alkoxides and enolates onto the triple bond were observed, and a thorough study of these reactions is reported here. © Wiley-VCH Verlag GmbH, 2000