不斉アルドール反応による立体制御

概要

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The natural products synthesis, in a way, represents a reaction sequence which almost unavoidably involves a chemical process of creating one or more additional chiral centers on a chiral substance with proper relative stereochemistry. This task demands, particularly in the construction of acylic systems, a combination of both an enantiomerically pure substance and reagent, as the diastereofacial selectivity of the reacting prochiral species constitutes a major factor in controlling the stereochemical course of reactions. This article elaborates on this fundamental problem of organic synthesis for which solutions are provided in the case of the aldol reaction, Several important aspects of aldol chemistry are covered : (1) the mechanism of the aldol reaction, (2) enolate geometry, (3) boron chiral enolates, and (4) coordination of a metal cation with the oxygen lone pair, with the central theme of diastereofacial stereoselection. Many fundamental findings made in this pursuit bring about an extremely powerful aldol strategy. The application of this strategy to the synthesis of 6-deoxyerythronolide B, the ansa chain of rifamycin S, and tylonolide, representing major macrolide metabolites of medium structural complexity, is also presented.
社団法人有機合成化学協会の論文