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.
Total Synthesis of (.+-.)-Gleenol and (.+-.)-Axenol via a Functionalized Spiro[4.5]decane
作者:Atsuo Nakazaki、Tomohiro Era、Susumu Kobayashi
DOI:10.1248/cpb.55.1606
日期:——
was accomplished through a readily available spiro[4.5]decane. The key features of the synthesis of 1 and 2 include Claisen rearrangement to afford the multi-functionalized spiro[4.5]decane 4 as a single diastereomer in excellent yield, installation of the C7 isopropyl group via ketene dithioacetal instead of direct alkylation and a diastereoselective reduction of ketone under the Birch conditions.