Intermolecular Halogenation/Esterification of Alkenes with <i>N</i>
-Halosuccinimide and Acetic Acid Catalyzed by 1,4-Diazabicyclo[2.2.2]octane
作者:Laura S. Pimenta、Elena V. Gusevskaya、Eduardo E. Alberto
DOI:10.1002/adsc.201700117
日期:2017.7.3
organocatalyst in the activation of N-chlorosuccinimide (NCS) towards the chlorination of alkenes. The chloriranium ion formed from NCS and the alkene, can be intermolecularly opened by a nucleophile, such as acetic acid, to produce highly functionalized trans-chloro esters in high yields. The protocol is also applied to the synthesis of chlorohydrins and chloro ethers using water or methanol as nucleophiles
1,4-二氮杂双环[2.2.2]辛烷(DABCO)是一种合适的路易斯碱,可在将N-氯代琥珀酰亚胺(NCS)活化以进行烯烃氯化反应中用作有机催化剂。由NCS和烯烃形成的氯离子可以通过亲核试剂(例如乙酸)在分子间打开,从而以高收率生产高度官能化的反氯酯。该协议还适用于使用水或甲醇作为亲核试剂代替乙酸来合成氯醇和氯醚的方法。溴代类似物也可以由烯烃和N合成-溴代琥珀酰亚胺(NBS)在各种碱性催化剂的存在下。但是,反应方式似乎有很大不同。发现碱在烯烃溴酯化中的催化性能受其布朗斯台德碱度的强烈影响,这表明由NBS和乙酸原位形成的乙酰基次溴酸盐在这些系统中充当真正的溴化剂。