Synthesis of new quinuclidine derivatives via Pd-mediated cross-coupling and cross-benzannulation reactions

New functionalized quinuclidines were prepared via palladium-catalyzed addition reactions of terminal alkynes (donors) to internal alkynes (acceptors). The enantiopure terminal alkynes were derivatives of quincoridine and quincorine, two semi-natural Cinchona alkaloids. The processes exhibited high chemoselectivity and excellent diastereoselectivity, the E-enynes being obtained as single products in almost all cases. The synthesis of new tetra and pentasubstituted benzene derivatives in good yields by [2+2+2] benzannulation of the diynes, obtained by the palladium-catalyzed homodimerization of 10,11-didehydro quincoridine and 10,11-didehydro quincorine, with terminal alkynes and in fair yield by [4+2] benzannulation of an enyne derivative of 10,11-didehydro quincoridine with 2,4-hexane-diyne are reported.

Figure optionsDownload as PowerPoint slide