Mild synthesis of mercaptonitriles from vinyl nitriles and their cyclization reactions
作者:Philip Caspari、Frank A. Nüesch、Antonia Neels、Dorina M. Opris
DOI:10.1039/c6ra21948a
日期:——
Thiol–ene addition of thioacetic acid A is widely used in the synthesis of thiols from vinyl precursors, but so far has not been conducted on non-conjugated vinyl nitriles. The challenge when vinyl nitriles are used is to selectively conduct the thiol–ene addition, while avoiding the nucleophilic addition of A to the nitrile group. We have found that vinyl nitriles give selective UV-induced thiol–ene
硫代乙酸A的硫醇-烯加成法广泛用于由乙烯基前体合成硫醇,但到目前为止,尚未在非共轭乙烯基腈上进行。使用乙烯基腈时,面临的挑战是选择性进行硫醇-烯加成,同时避免将A亲核加成至腈基。我们发现,只要存在化学引发剂量的A,乙烯基腈在光引发剂的存在下就能选择性地诱导UV诱导的硫醇-烯加成反应。乙烯基基团上可以使用乙烯基,并且使用空间上不受阻碍的乙烯基。相反,当使用位阻乙烯基时,腈的亲核加成是有利的。所制备的硫醇腈在碱性和酸性条件下以及在硅胶存在下均可轻松进行环化反应。这说明了腈对硫醇添加的高反应性。1,2-乙二硫醇B是A的替代试剂,因为它允许在温和的和非酸性的反应条件下将乙烯基腈直接转化为硫醇。