Positional isomerization of quinine and quinidine via rhodium on alumina catalysis: practical one-step synthesis of Δ3,10-isoquinine and Δ3,10-isoquinidine

Published in: Journal, Volume : 44, Issue : 28, Pages : 5365-5368

DOI : 10.1016/s0040-4039(03)01180-8

Author : Portlock, David E.; Naskar, Dinabandhu; West, Laura; Seibel, William L.; Gu, Titan; Krauss, Howard J.; Peng, X. Sean; Dybas, Paul M.; Soyke, Edward G.; Ashton, Stephen B.; Burton, Jonathan

Abstract : The synthesis of Δ3,10-isoquinine (5Z,5E) and Δ3,10-isoquinidine (6Z,6E) was achieved in one-step through positional isomerization of the terminal alkene in the parent cinchona alkaloids using catalytic amounts of 5% Rh/Al2O3 and excess hydrochloric acid in refluxing 50% aqueous EtOH. The products were obtained in good yields as a mixture of E and Z geometric isomers and fully characterized using spectroscopic methods.