Asymmetric Synthesis of <i>cis</i>-7-Methoxycalamenene via the Intramolecular Buchner Reaction of an α-Diazoketone
作者:Paul A. McDowell、David A. Foley、Patrick O’Leary、Alan Ford、Anita R. Maguire
DOI:10.1021/jo202499j
日期:2012.2.17
The asymmetric synthesis of cis-7-methoxycalamenene 1 has been accomplished using the intramolecular Buchner reaction of α-diazoketone 7 as the key step in the synthetic route. Upon reduction of the equilibrating azulenone structure 8, the resulting azulenol 9 rearranges to dihydronaphthalene 10 containing the 6,6-membered bicyclic ring system characteristic of 1, by means of an acid-catalyzed aromatization
Enantioselective synthesis of cis-7-methoxy-calamenene via Claisen rearrangement of an enzymatically resolved allyl alcohol
作者:Elisabetta Brenna、Claudia Dei Negri、Claudio Fuganti、Francesco G. Gatti、Stefano Serra
DOI:10.1016/j.tetasy.2003.11.021
日期:2004.1
An enantioselective synthesis of cis-7-methoxy-calamenene 1 has been accomplished through the following key-steps: (i) enzymatic resolution of the racemic allyl alcohol 3 to furnish the (R)-enantiomer (ee >99%); (ii) Claisen-orthoester rearrangement of 4 to introduce the isopropyl unit on the benzylic position (99% ee); (iii) diastereoselective reduction of dihydronaphthalene derivative 11 to give the cis-isomer 12 (98% de); (iv) regioselective introduction of the formyl group by a Vilsmeier reaction followed by reduction to give 1. (C) 2003 Elsevier Ltd. All rights reserved.