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Note | Regular issue | Vol 48, No. 12, 1998, pp.2621-2630
Published online, 1st January, 1970
DOI: 10.3987/COM-98-8296
■ Studies on Diastereoselective Synthesis of 3-Vinyl-5-carbomethoxy-2-oxabicyclo[3.3.0]octane Derivatives Employing Palladium(II) Oxidative Cyclization

Emerson Poley Peçanha, Carlos Alberto Manssour Fraga, and Eliezer Jesus Barreiro*

*Laboratório de Avaliação e Síntese de Substâncias Bioativas, Faculdade de Farmácia, Universidade Federal do Rio de Janeiro, Centro de Ciências da Saúde, P.O.Box 68006, Rio de Janeiro RJ 21944-970, Brazil

Abstract

3-α,β-Vinyl-5-carbomethoxy-2-oxabicyclo[3.3.0]octane derivatives (7a,b) were synthesized through heterocyclization of alcohols trans- and cis-2-[(E)-buten-2-yl-1-]-2-carbomethoxycyclopentanols (5a,b) employing a palladium acetate / cupric acetate catalytic system. This cyclization process was diastereoselective, favoring the formation of 3β-vinyl (exo) diastereomer (7b). In addition, the employ of adequate solvent system, i.e. isopropanol/water, could prevent a ketalization side reaction verified in methanol/water.