Spiroannelation via intramolecular ketocarbenoid addition. Stereocontrolled synthesis of (-)-acorenone B and (.+-.)-. alpha.-chamigrene

…, JF Ruppert, MA Avery, S Torii, J Nokami

Index: White, James D.; Ruppert, John F.; Avery, Mitchell A.; Torii, Sigeru; Nokami, Junzo Journal of the American Chemical Society, 1981 , vol. 103, # 7 p. 1813 - 1821

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Citation Number: 56

Abstract

Abstract: The spirobicyclic structures of (&)-a-chamigrene (7) and (-)-acorenone B (6) were synthesized by means of a copper-catalyzed, intramolecular cycloaddition of diazo ketones 25 and 47, respectively. The former was prepared from 4-methyl-4-@-methoxyphenyl) pentanoic acid (8) and the latter was obtained in optically active form from (R)-(+)-limonene (35). Reduction of 26 with lithium in ammonia gave 27, which was transformed to (f)-a- ...