An Experimental and Theoretical Study on the Remarkable Influence of Protecting Groups on the Selectivity of Addition of Amines to Vinyl Sulfone-Modified Hex-2-enopyranosides
作者:Rahul Bhattacharya、Manoj K. Kesharwani、Chinmoy Manna、Bishwajit Ganguly、Cheravakattu G. Suresh、Tanmaya Pathak
DOI:10.1021/jo902046g
日期:2010.1.15
calculations suggest that the Michael addition of amines and proton transfer to vinyl sulfone-modified carbohydrates 2α and 5α are possible via relay process in a concerted mechanism. These calculations reveal that the addition of primary amines to vinyl sulfone-modified carbohydrate is preferential due to the low activation energy barriers, whereas the addition of secondary amines has relatively higher activation
尽管苯基亚甲基保护的乙烯基砜改性的碳水化合物2α以迈克尔的方式与伯胺和仲胺反应生成胺化产物,但只有伯胺与二苄基保护的3α,6 - O-三苯甲基保护的4α和未保护的5α反应。保护基团首次对乙烯基砜改性的碳水化合物的反应方式产生了显着影响。量子化学计算表明胺的迈克尔加成和质子转移到乙烯基砜改性的碳水化合物2α和5α通过协调机制中的中继过程是可能的。这些计算表明,由于低的活化能垒,向乙烯基砜改性的碳水化合物中添加伯胺是优选的,而仲胺的添加具有相对较高的活化能垒。理论结论与实验结果相符。