Silicon guided rearrangement of epoxydecalines to spirocyclic compounds. Synthesis of gleenol and axenol from carvone
摘要:
The synthesis of the spirocyclic sesquiterpenes (-)-gleenol and (-)-axenol in enantiomerically pure form has been achieved starting from R-(-)-carvone. The key step is the silicon guided acid-promoted rearrangement of a 9-trimethylsilyl-5,6-epoxy-noreudesmane prepared from 3-tiimethylsilyldihydrocarvone in several steps involving Robinson annulation, enone deconjugation and epoxidation. Acid treatment of the epoxy-noreudesmane gave a norspiroaxane as the main product, which was used as intermediate for the synthesis of two naturally occurring sesquiterpenes gleenol and axenol. (c) 2005 Elsevier Ltd. All rights reserved.
Cyclic (E)-β-trimethylsilylketoxime acetates were effectively cleaved by a catalytic action of trimethylsilyl trifluoromethanesulfonate to give the corresponding unsaturated nitriles. The fragmentation in the Beckmann rearrangement is completely controlled and directed by trimethylsilyl group to lead regio- and stereospecific formation of the double bond.
Silicon guided rearrangement of epoxydecalines to spirocyclic compounds. Synthesis of gleenol and axenol from carvone
作者:Gonzalo Blay、Ana M. Collado、Begoña García、José R. Pedro
DOI:10.1016/j.tet.2005.09.025
日期:2005.11
The synthesis of the spirocyclic sesquiterpenes (-)-gleenol and (-)-axenol in enantiomerically pure form has been achieved starting from R-(-)-carvone. The key step is the silicon guided acid-promoted rearrangement of a 9-trimethylsilyl-5,6-epoxy-noreudesmane prepared from 3-tiimethylsilyldihydrocarvone in several steps involving Robinson annulation, enone deconjugation and epoxidation. Acid treatment of the epoxy-noreudesmane gave a norspiroaxane as the main product, which was used as intermediate for the synthesis of two naturally occurring sesquiterpenes gleenol and axenol. (c) 2005 Elsevier Ltd. All rights reserved.
Rearrangement of 4,5-Epoxy-9-trimethylsilyldecalines. Application to the Synthesis of the Natural Eremophilane (−)-Aristolochene
作者:Gonzalo Blay、Luz Cardona、Ana M. Collado、Begoña García、José R. Pedro
DOI:10.1021/jo060643i
日期:2006.6.1
ilyl-eudesmanes and 15-nor-eudesmanes, having different relative stereochemistry and substitution at the oxirane ring, have been prepared starting from (−)-carvone and subjected to acid-promoted rearrangement. The presence of the silicon at C9 favors two different main reaction pathways involving C14-methyl or C1-methylene migration through the stabilization of a C10 carbocation intermediate. Selective