An investigation of the observed, but counter-intuitive, stereoselectivity noted during chiral amine synthesis via N-chiral-ketimines

作者：Nugent Thomas C^*; Williams Richard Vaughan; Dragan Andrei; Mendez Alejandro Alvarado; Iosub Andrei V

来源：Beilstein Journal of Organic Chemistry, 2013, 9: 2103-2112.

DOI：10.3762/bjoc.9.247

• chiral amines
• cis/trans isomerization
• imine isomerization
• imine reduction
• reductive amination

The default explanation for good to high diastereomeric excess when reducing N-chiral imines possessing only mediocre cis/trans-imine ratios (%26gt; 15% cis-imine) has invariably been in situ cis-to-trans isomerization before reduction; but until now no study unequivocally supported this conclusion. The present study co-examines an alternative hypothesis, namely that some classes of cis-imines may hold conformations that erode the inherent facial bias of the chiral auxiliary, providing more of the trans-imine reduction product than would otherwise be expected. The ensuing experimental and computational ( DFT) results favor the former, pre-existing, explanation.

• 出版日期2013-10-15