Lewis Acid-catalysed Aza-Diels-AlderversusMannich Reactions ofN-Diethyl Phosphoryl Imino Dienophiles with Oxygenated Dienes and Application of a Chiral Lewis Acid
Lewis Acid-catalysed Aza-Diels-Alder<i>versus</i>Mannich Reactions of<i>N</i>-Diethyl Phosphoryl Imino Dienophiles with Oxygenated Dienes and Application of a Chiral Lewis Acid
作者:Andrew Whiting、Lorenzo Di Bari、Stéphane Guillarme、Stephen Hermitage、Judith A. Howard、David A. Jay、Gennaro Pescitelli、Dmitrii S. Yufit
DOI:10.1055/s-2004-817742
日期:——
N-Phosphoryl imines react with oxygenated dienes in the presence of Lewis acids to provide either the formal aza-Diels-Alder adduct, or the acyclic Mannich-type addition product, depending upon the catalyst and work up used, which is in agreement with the hypothesis that these reactions are mediated by zwitterionic Lewis acid-complex intermediates, rather than a concerted cycloaddition transition-state followed by hydrolytic ring opening. Stoichiometric asymmetric induction can be achieved using a zinc(II)-binol complex, producing up 77% ee.