We have developed a nickel-catalyzedcross-coupling reaction of cyclic alkenyl ethers with arylboronic esters that leads to the formation of unsaturated alcohols via ring-opening by the cleavage of a C(sp2)–O bond. The use of 1,3-dicyclohexylimidazol-2-ylidene as the ligand is essential to promote this cross-coupling process.
Enantioselective Bromocycloetherification by Lewis Base/Chiral Brønsted Acid Cooperative Catalysis
作者:Scott E. Denmark、Matthew T. Burk
DOI:10.1021/ol203033k
日期:2012.1.6
A binary catalyst system for the enantioselective bromocycloetherification of 5-arylpentenols is described. The combination of an achiral Lewis base and a chiralBrønstedacid affords good enantioselectivities for the cyclization of Z configured 5-arylpentenols to form bromomethyltetrahydrofurans. The constitutional site selectivity is highly dependent upon the aromatic substituent and the configuration