Addition to steroid polyenes—II Reaction of 7-dehydrocholesteryl acetate with dimethyl acetylenedicarboxylate |
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| Authors: | A van der Gen J Lakeman U K Pandit and H O Huisman |
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| Institution: | Laboratory of Organic Chemistry, University of Amsterdam, The Netherlands |
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| Abstract: | Dimethyl acetylenedicarboxylate reacts with 7-dehydrocholesteryl acetate (I) by nucleophilic addition at C7. Two products are obtained, resulting from subsequent hydrogen abstraction from C9 (II) and from C14 (III) respectively. Addition-abstraction, hitherto unreported for esters of acetylenedicarboxylic acid, appears to be the sole reaction mode with this highly hindered diene-system. Structure proof is supported by NMR spectroscopy as well as by chemical transformations of the adducts. On treatment with base one of the adducts undergoes a prototropic rearrangement. |
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