Improved Synthesis of Mono- and Disubstituted 2-Halonicotinonitriles from Alkylidene Malononitriles
作者:Ashley R. Longstreet、Brian S. Campbell、B. Frank Gupton、D. Tyler McQuade
DOI:10.1021/ol4025265
日期:2013.10.18
with 2,3,4 and/or 5 substitution remain challenging to prepare. Existing strategies to form multisubstituted 2-halonicotinonitriles via enamines suffer from dimerization of the starting alkylidene malononitriles resulting in low yields. Through alteration of reaction conditions, a new high yielding method into enamines was realized by condensing DMF–DMA and alkylidene malononitriles in the presence of
具有2,3,4和/或5取代基的吡啶仍然难以制备。现有的通过烯胺形成多取代的2-卤代丁腈的策略遭受起始亚烷基丙二腈的二聚作用,导致收率低。通过改变反应条件,通过在亚化学计量的乙酸酐存在下使DMF-DMA和亚烷基丙二腈缩合,实现了一种新的高产率烯胺化方法。在Pinner条件下环化所得的烯胺以高总收率提供了2-卤代丁腈。