Asymmetric Petasis Reactions Catalyzed by Chiral Biphenols
作者:Sha Lou、Scott E. Schaus
DOI:10.1021/ja8018934
日期:2008.6.1
Chiralbiphenolscatalyze the enantioselective Petasis reaction of alkenyl boronates, secondary amines, and ethyl glyoxylate. The reaction requires the use of 15 mol % of (S)-VAPOL as the catalyst, alkenyl boronates as nucleophiles, ethyl glyoxylate as the aldehyde component, and 3 A molecular sieves as an additive. The chiral alpha-amino ester products are obtained in good yields (71-92%) and high
Stereospecific Synthesis of Vinyl(phenyl)iodonium Tetrafluoroborates via Boron-Iodane Exchange of Vinylboronic Acids and Esters with Hypervalent Phenyliodanes
Reaction of vinylboronic acids and esters with hypervalent phenyliodanes in the presence of BF3-Et2O undergoes boron-iodane exchange at O degrees C in dichloromethane yielding vinyl(phenyl)iodonium tetrafluoroborates stereoselectively with retention of configuration. (C) 1997 Elsevier Science Ltd.