STEREOCHEMICAL FEATURES OF PALLADIUM-CATALYZED ALLYLIC CARBONYLATION OF ACYCLIC TERPENES

During the study on the synthesis of straight- and short-chain fatty acids by allylic carbonylation, we used derivatives of acyclic terpenes (III-V) to determine the stereochemistry of the allylic carbonylation. It is shown that the completely different isomer distribution of 4,8-dimethyl-3,7-nonadienoate obtained from the catalytic reaction of the geranyl (III) and neryl (IV) systems indicates that the carbonylation is much faster than the syn-anti isomerization of the pi -allylpalladium complexes, especially in the presence of halide-free palladium catalyst. Namely, the palladium-catalyzed allylic carbonylation occurs before the syn-anti equilibrium is attained; thus it is a kinetically controlled process.