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Fleming−Tamao Oxidation and Masked Hydroxyl Functionality:  Total Synthesis of (+)-Pramanicin and Structural Elucidation of the Antifungal Natural Product (−)-Pramanicin

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journal contribution
posted on 23.07.1999, 00:00 by Anthony G. M. Barrett, John Head, Marie L. Smith, Nicholas S. Stock, A. J. P. White, D. J. Williams
The total synthesis of (+)-pramanicin (41b) is reported, thereby establishing the relative and absolute stereochemistry of the naturally occurring antifungal agent. The key steps involve (i) conjugate addition of the diethyl((diethylamino)diphenylsilyl)zincate to a suitably protected γ-lactam 3 and quenching of the resultant enolate with the α,β-unsaturated γ,δ-epoxy aldehyde 2 (X = H), (ii) Ni(acac)2-catalyzed hydroxylation of a β-dicarbonyl array, and (iii) Fleming−Tamao oxidation to reveal the masked C-3 hydroxyl group.