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RESEARCH PRODUCT

ChemInform Abstract: Diastereoselectivity in Organometallic Additions to the Carbonyl Group of Protected Erythrulose Derivatives.

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We have investigated a number of nucleophillic additions to l-erythrulose derivatives (4−12) bearing protective O-silyl, O-benzyl, and O-trityl groups in various relative positions. The results are discussed in the frame of chelated vs nonchelated transition states with additional support of previously published theoretical calculations. Sound evidence appears to exist for the formation of α-chelates as the key intermediates in nucleophillic additions to these α,β-dioxygenated ketones. Since such evidence is still lacking in the case of β-chelates, proposals of their intermediacy have been relegated in favor of the more solid Felkin−Anh model, which predicts the same stereochemical result. The behavior of these highly functionalized ketones does not always match that of structurally similar aldehydes.