Stereospecific Dicobalt Octacarbonyl Mediated Enyne Cyclization for the Enantiospecific Synthesis of a 6a-Carbocycline Analogue

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Journal of the American Chemical Society





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ACS Publications


D-(+)-Ribonolactone 5 was converted into the butenolide 7 by pyrolysis of the derived ortho ester. Treatment of 7 with trisyl bromide gave the corresponding trisylate 9, which was converted into 10 by using Li,(CH,=CH),CuCN. Exposure of 10 to potassium carbonate in methanol gave epoxide 12, which underwent ring opening when treated with lithium (tri- methylsi1yl)acetylide-BF,.OEt, to give lactone 13. Reduction of lactone 13 with LiAlH, gave diol 18, which was converted into its derived acetonide 19. When 19 was treated with CO,(CO)~/CO/P~,PO, bicyclo[3.3.0]octenone 21 was formed in a highly stereoselective process. Conversion of 21 into the carbocycline analogue 28 was achieved by standard methods. The absolute configuration of 21 was established by single-crystal X-ray crystallography on the derived bis(p-bromobenzylidene) derivative 24.


Author Posting © American Chemical Society, 1987. This article is posted here by permission of the American Chemical Society for personal use, not for redistribution. The article was published in J. Am. Chem. Soc., 1987, Volume 109, Issue 24. http://dx.doi.org/10.1021/ja00258a040

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