Chemistry Letters, Vol.36, No.11, 1338-1339, 2007
Enantioselecitve elimination of Pd-H from eta(3)-allylpalladium-Tol BINAP complexes. Evidence of syn elimination pathway
The palladium-catalyzed elimination of the bicyclic cis-acetate 1b using Pd catalyst and (R)-p-Tol BINAP gave the (S)-diene 2 with 58% ee. Bicyclic eta(3)-allylpalladium complex 3a with (R)-p-Tol BINAP, considered as an intermediate in the catalytic reaction from 1b, was prepared. Enantioselectivity in decomposition of 3a is dependent on the reaction conditions. The thermal decomposition of 3a without base gave the (S)-2 with 70% ee. However, the decomposition of 3a in the presence of excess base gave (R)-2 with 58% ee. Syn elimination from 3a was found to proceed preferentially from the decomposition results of the deuterium-labeled complexes.