Amidopalladation of Alkoxyallenes Applied in the Synthesis of an Enantiopure 1-Ethylquinolizidine Frog Alkaloid

A palladium-catalyzed amidation of alkoxyallenes has been developed for the construction of linear allylic N,O-acetals under basic conditions involving (cyclic) amides, sulfonamides, carbamates, and amidophosphates. Application of the methodology provided access to the enantiopure 1-ethylquinolizidine structural motif, which is a key synthon in the synthesis of the naturally occurring poisonous frog quinolizidine 233A and derivatives such as the 1-epi-isomer of quinolizidine 207I.