A novel regioselective Heck-vinylation of enamides. Investigation of fluorous-tagged bidentate ligands for rapid separation

ORGN 359

Karl S. A. Vallin1, Qisheng Zhang2, Mats Larhed1, Dennis P. Curran2, and Anders Hallberg3. (1) Department of Organic Pharmaceutical Chemistry, Uppsala University, BMC, Box-574, SE-751 23 Uppsala, Sweden, (2) Department of Chemistry, University of Pittsburgh, 219 Parkman Ave., Pittsburgh, PA 15260, (3) Department of Organic Pharmaceutical Chemistry, BMC, Uppsala University, Box 596, S-75124 Uppsala, Sweden

We have performed internal ligand-controlled Heck vinylations of enamides with high regioselectivity in moderate to good yields. New bidentate fluorous-tagged 1,3-bis(diphenylphosphino) propane ligands (F-dppp’s) were synthesized and examined. The cationic vinylations of the enamides with F-dppp ligands rendered essentially the same internal selectivity and catalytic activity as in those vinylations where non-fluorous ligands were employed. After reaction, the fluorous-tagged ligand material was easily removed by convenient solid fluorous phase separation. In addition, controlled microwave heating accelerated the palladium-catalyzed reactions and full conversions were achieved after reaction times of only 15-30 min.