Novel synthetic methods for the preparation of optically active fluorine-containing building blocks on the basis of sigmatropic rearrangements

Optically active gamma-fluoroalkylated allylic alcohols were prepared via various synthetic protocols such as enzymatic resolution of the racemate, difluorocarbene-mediated reaction, and a novel 1, 3-allylic rearrangement of alpha-fluoroalkylcarbinols. Thus-obtained allylic alcohols could participate nicely in various sigmatropic rearrangements such as Johnson-, Eshenmoser-, Ireland-Claisen, and [2, 3]-Wittig shifts, to give the corresponding rearranged products with excellent stereoselectivity in good to high yields. The sequential operation of 1, 3-allylic shift and the following Ireland-Claisen rearrangement realized the one-pot synthesis of the multifunctionalized building blocks in high yields from easily accessible alpha-fluoroalkylated carbinols. The Ireland-Claisen products underwent iodolactonization and osmylation, gamma-lactones with four successive chiral centers being afforded in a highly stereoselective manner.