Highly stereoselective synthesis of 6-perfluoroalkyl-6-fluoroalka-2,3,5-(Z)-trienols through carbometallation-elimination of 5-perfluoroalkyl-substituted 4(E)-alken-2-ynols with Grignard reagents

A highly regio- and stereoselective sequential carbometallation and Z-selective β-elimination reaction of 5-perfluoroalkyl-4(E)-en-2-ynols with Grignard reagents in Et2O has been developed to afford various 6-perfluoroalkyl-6-fluoroalka-2,3,5(Z)-trienols in good to excellent yields. Primary or secondary alkyl or aryl Grignard reagents may be used to introduce the R2 group to the 2-position of the starting materials referring to the hydroxyl group. A mechanism for this transformation has been proposed.