Davies H M, Calvo R L, Townsend R J, Ren P, Churchill R M
Department of Chemistry, State University of New York at Buffalo, 14260-3000, USA.
J Org Chem. 2000 Jul 14;65(14):4261-8. doi: 10.1021/jo991959b.
The intramolecular type II [3 + 4] cycloaddition between vinylcarbenoids and furans is a practical method for the construction of 5-oxo-10-oxatricyclo[6.2.1.0(4,9)]undeca-3, 8(11)-dienes, containing two anti-Bredt double bonds. These tricyclic systems are well functionalized for eventual elaboration to the natural product CP-263,114. The rhodium-stabilized vinylcarbenoids are generated by dirhodium tetracarboxylate catalyzed decomposition of vinyldiazoacetates. The [3 + 4] cycloaddition is generally considered to occur by a tandem cyclopropanation/Cope rearrangement, although evidence is presented that with these substrates the [3 + 4] cycloaddition may occur in a concerted manner.
乙烯基类卡宾与呋喃之间的分子内II型[3 + 4]环加成反应是构建含有两个反式布瑞德双键的5-氧代-10-氧杂三环[6.2.1.0(4,9)]十一碳-3,8(11)-二烯的实用方法。这些三环体系具有良好的官能团化特性，可最终转化为天然产物CP-263,114。铑稳定的乙烯基类卡宾由四羧酸二铑催化乙烯基重氮乙酸酯的分解产生。虽然有证据表明这些底物的[3 + 4]环加成可能以协同方式发生，但[3 + 4]环加成通常被认为是通过串联环丙烷化/Cope重排进行的。
