Lithium Alkoxides of Cinchona Alkaloids as Chiral Controllers for Enantioselective Acetylide Addition to Cyclic N-Acyl Ketimines
摘要:
Highly enantioselective acetylide addition to cyclic N-acyl ketimines 1 can be carried out using the lithium alkoxide of quinine as a stoichiometric chiral additive. Quinidine can be used to give the opposite enantiomer. Optimization of temperature is critical, with low or high temperatures reducing selectivity. Using the bulky 9-anthrylmethyl protecting group at a distal position on the imine, a 97% ee was achieved and applied to the asymmetric synthesis of HIV reverse transcriptase inhibitor 3.
Lithium Alkoxides of Cinchona Alkaloids as Chiral Controllers for Enantioselective Acetylide Addition to Cyclic N-Acyl Ketimines
摘要:
Highly enantioselective acetylide addition to cyclic N-acyl ketimines 1 can be carried out using the lithium alkoxide of quinine as a stoichiometric chiral additive. Quinidine can be used to give the opposite enantiomer. Optimization of temperature is critical, with low or high temperatures reducing selectivity. Using the bulky 9-anthrylmethyl protecting group at a distal position on the imine, a 97% ee was achieved and applied to the asymmetric synthesis of HIV reverse transcriptase inhibitor 3.