Practical Synthesis of 1-Aryl-6-(hydroxymethyl)-2-ketopiperazines via a 6-exo Amide−Epoxide Cyclization
摘要:
Chiral 1-aryl-6-(hydroxymethyl)-2-ketopiperazines can be prepared via an operationally simple, 6-exo epoxide ring-opening cyclization to form the ketopiperazine C6-N1 bond in high yields and with excellent enantiomeric purity.
Practical Synthesis of 1-Aryl-6-(hydroxymethyl)-2-ketopiperazines via a 6-<i>exo</i> Amide−Epoxide Cyclization
作者:Noel A. Powell、Fred L. Ciske、Emma C. Clay、Wayne L. Cody、Dennis M. Downing、Peter G. Blazecka、Daniel D. Holsworth、Jeremy J. Edmunds
DOI:10.1021/ol048235t
日期:2004.10.1
Chiral 1-aryl-6-(hydroxymethyl)-2-ketopiperazines can be prepared via an operationally simple, 6-exo epoxide ring-opening cyclization to form the ketopiperazine C6-N1 bond in high yields and with excellent enantiomeric purity.
Nucleophilic substitution reactions of α-chloroacetanilides with benzylamines in dimethyl sulfoxide
作者:Ki Sun Lee、Keshab Kumar Adhikary、Hai Whang Lee、Bon-Su Lee、Ikchoon Lee
DOI:10.1039/b300477e
日期:——
Kinetic studies of the reactions of alpha-chloroacetanilides (YC6H4NRC(=O)CH2Cl; R = H (5) and CH3 (6)) with benzylamines (NH2CH2C6H4X) were carried out in dimethyl sulfoxide at 55.0 degrees C. The Brønsted betaX values were in the range from 0.6 to 0.9 and cross-interaction constants phoXY were positive: phoXY = +0.21 and +0.18 for 5 and 6, respectively. The rates were faster with 6 than with 5 and
在55.0摄氏度下于二甲亚砜中进行了α-氯代乙酰苯胺(YC6H4NRC(= O)CH2Cl; R = H(5)和CH3(6))与苄胺(NH2CH2C6H4X)反应的动力学研究。布朗斯台德betaX值为在0.6到0.9的范围内,交叉相互作用常数phoXY为正:5和6的phoXY分别为+0.21和+0.18。用6的速率比用5的速率快,并且获得了涉及氘化苄胺(ND2CH2C6H4X)亲核试剂的反向次级动力学同位素效应,kH / kD <1.0。基于这些结果和其他结果,提出了一种分步机理,其具有限速地从两性离子四面体中间体T +/-中排出氯化物离去基团。在这种机理中,先将羰基加到T +/-中,然后再以桥联型过渡态将氯化物排出。