A convergent synthesis of the [4.4]-spiroacetal-γ-lactones cephalosporolides E and F
摘要:
A short convergent synthesis of the fungal metabolites cephalosporolides E and F is reported. The key step makes use of a chelation-controlled Mukaiyama aldol reaction to access the key acyclic spiroacetal precursor with the required syn stereochemistry. (C) 2010 Elsevier Ltd. All rights reserved.
Asymmetric Synthesis of Allylsilanes by the Borylation of Lithiated Carbamates: Formal Total Synthesis of (−)-Decarestrictine D
作者:Michael Binanzer、Guang Yu Fang、Varinder K. Aggarwal
DOI:10.1002/anie.201001223
日期:——
carbamates react with retention of configuration, thereby providing enantio‐complementary routes to β‐hydroxy allylsilanes (see scheme). The methodology has been applied in a concise formal totalsynthesis of (−)‐decarestrictineD.
Heteroatom-substituted aldehydes 3, 4, and 5 were subjected to Mukaiyamareactions with silylenolether 10. The reaction of the new trifluoromethyl-substituted aldehyde 3 with 10 afforded γ-lactone 11 with excellent trans selectivity. In contrast, the known benzyloxy-substituted aldehyde 4 and 10 provided γ-lactone 13 without any selectively in the presence of BF3 as the promoting Lewis acid; use