time with the new resolving agent (R,R)- and (S,S)-2,3-di(phenylamino-carbonyl)tartaric acid (5c) (40–45% weight yields; >99% ee). The diamines (R)- or (S)-2a and 2b were converted with >98% stereochemical retention into the diiodides (R)- and (S)-3a and 3b and subsequently, without loss of optical purity, diphenylphosphinated to the known diphosphines (R)- and (S)-4a and 4b.
Enantioselective Aziridination Using Copper Complexes of Biaryl Schiff Bases
作者:Kevin M. Gillespie、Christopher J. Sanders、Paul O'Shaughnessy、Ian Westmoreland、Christopher P. Thickitt、Peter Scott
DOI:10.1021/jo025515i
日期:2002.5.1
Racemic2,2'-diamino-6,6'-dimethylbiphenyl is resolved using simulated moving bed chromatography, and the absolute configuration of the enantiomers is confirmed via the X-ray crystal structure of a derivative. The diamine is condensed with a range of aldehydes to give bidentate aldimine proligands L. Molecular structures of the complexes formed between L and Cu(I) fall into two classes; bimetallic
are readily prepared from the direct reaction between amides and diaryliodonium salts. As demonstrated for 24 different examples, the reaction is of unusually broad scope with respect to the sterically congested arene and the nitrogen source, occurs without the requirement for any additional promoter, and proceeds through a direct reductive elimination at the iodine(III) center. The efficiency of the
Biphenyl-Based Bis(thiourea) Organocatalyst for Asymmetric and syn-Selective Henry Reaction
作者:Pavel Bobal、Jan Otevrel
DOI:10.1055/s-0036-1588594
日期:——
excellent enantioselectivities. The achieved high reactivity and enantioselectivity in the nitroaldol reaction of nitroalkanes with aromatic aldehydes suggests promising potential for this catalyst. Moreover, a significant syn-diastereoselectivity was observed. A scalable, efficient and chromatography-free synthesis of a new enantiopure C 2-symmetric bis(thiourea) catalyst was accomplished from a readily