Organocatalytic Asymmetric Mannich Cyclization of Hydroxylactams with Acetals: Total Syntheses of (−)-Epilupinine, (−)-Tashiromine, and (−)-Trachelanthamidine
作者:Dipankar Koley、Yarkali Krishna、Kyatham Srinivas、Afsar Ali Khan、Ruchir Kant
DOI:10.1002/anie.201407185
日期:2014.11.24
cyclization between a hydroxylactam and acetal is described to provide fused, bicyclic alkaloids bearing a bridgehead N atom. Both aliphatic and aromatic substrates were used in this transformation to furnish chiral pyrrolizidinone, indolizidinone, and quinolizidinone derivatives in up to 89 % yield and 97 % ee. The total syntheses of (−)‐epilupinine, (−)‐tashiromine, and (−)‐trachelanthamidine also
Remote Control of Diastereoselectivity in Intramolecular Reactions of Chiral Allylsilanes
作者:Weston R. Judd、Sooho Ban、Jeffrey Aubé
DOI:10.1021/ja063411+
日期:2006.10.1
During investigations of cyclization reactions between chiral allylsilanes and N-acyliminiumions, it was discovered that a suitably positioned benzyloxy group on the allylsilane component caused a reversal in the diastereoselectivity of these reactions relative to that normally observed with alkyl-substituted allylsilanes. This effect was subsequently observed in two other reaction types. Investigations