Synlett 2006(10): 1527-1530  
DOI: 10.1055/s-2006-941599
LETTER
© Georg Thieme Verlag Stuttgart · New York

Enantioselective Synthesis of Bicyclo[4.4.1]undecane-2,7-dione via ­Samarium(II)-Mediated Fragmentation of a Cyclopropane Precursor

Sherif El Sheikh, Nina Kausch, J. Lex, J.-M. Neudörfl, Hans-Günther Schmalz*
Institut für Organische Chemie, Universität zu Köln, Greinstr. 4, 50939 Köln, Germany
Fax: +49(221)4703064; e-Mail: schmalz@uni-koeln.de;
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Publikationsverlauf

Received 4 April 2006
Publikationsdatum:
12. Juni 2006 (online)

Abstract

An efficient six-step synthesis of bicyclo[4.4.1]undecane-2,7-dione was elaborated. Key steps include an enantioselective oxazaborolidine-catalyzed borane reduction (CBS reduction) of 2,3,4,6,7,8-hexahydronaphthalene-1,5-dione to the corresponding diol, and a subsequent (syn-diastereoselective) cyclopropanation. Oxidation then gives tricyclo[4.4.1.01,6]undecane-2,7-dione (>99% ee) which on treatment with two equivalents of samarium(II) iodide undergoes cleavage of the central cyclopropane bond to yield the target compound without any loss of stereochemical information.