Controlling the position of the nucleophilic ring-opening of 2-EWG-substituted azetidinium salts with fluoride by the N-1-(1-naphthyl)ethyl substituent and BINAM-derived bis-urea organocatalyst
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引用次数: 0
Abstract
BINAM (1,1′-binaphthyl-2,2′-diamine)-derived bis-urea-catalyzed nucleophilic ring-opening of optically active and diastereomerically pure 2-EWG (electron-withdrawing group)-substituted N-(1-(1-naphthyl)ethyl)azetidinium salts with cesium fluoride in dichloromethane at room temperature proceeds at the less sterically hindered 4-position over the electronically deficient 2-position. Selective ring-opening at the 4-position is achieved by the combination of chiral stereocenters, as in N-(1-(1-naphthyl)ethyl)azetidinium salt, and steric bulk of the chiral bis-urea catalysts. The reaction affords the corresponding γ-fluoro-α-aminobutyric acid derivatives in diastereomerically pure. This protocol is applicable to the synthesis of enantiomerically enriched (98 % ee) γ-fluoro-α-amino acid derivatives starting from the commercially available chiral 1-(1-naphthyl)ethylamine.
期刊介绍:
Tetrahedron publishes full accounts of research having outstanding significance in the broad field of organic chemistry and its related disciplines, such as organic materials and bio-organic chemistry.
Regular papers in Tetrahedron are expected to represent detailed accounts of an original study having substantially greater scope and details than that found in a communication, as published in Tetrahedron Letters.
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