(+)-(S)-Angustureine was synthesized using a CuI-catalyzed coupling reaction of iodobenzene with an enan-tiopure -amino ester as the key step. The overall yield is 36% in 7 linear steps.
Reduction of azides to amines without touching benzyl, t-butyldimethylsilyl, t-butyldiphenylsilyl, trityl and tetrahydropyranyl ether protecting groups, C-C double and triple bond, as well as aromatic bromide and nitrile functional groups, was achieved using sodium amalgam as a reducing reagent in methanol at temperature from -40℃ to room temperature. However, ester group was reduced under this condition.
