Regioselective Dearomatization of
<i>N</i>
‐Alkylquinolinium and Pyridinium Salts under Morita‐Baylis‐Hillman Conditions
作者:Abhishek Pareek、Marcin Kalek
DOI:10.1002/adsc.202200429
日期:2022.8.16
activating the electron-poor olefin as well as a base. The dearomatization occurs regioselectively at the C-2 position, delivering a broad range of α-(1,2-dihydroquinolin-2-yl)vinyl esters, ketones, and sulfones. The scope of the transformation has also been extended to N-alkylpyridinium salts. For this class of substrates a presence of at least moderately electron-withdrawing substituent in the ring is necessary
Morita-Baylis-Hillman 反应采用N-烷基喹啉鎓盐作为亲电试剂。该反应由 DBU 促进,它既可以作为催化剂激活贫电子烯烃,也可以作为碱。脱芳构化作用在 C-2 位区域选择性地发生,产生范围广泛的 α-(1,2-dihydroquinolin-2-yl) 乙烯基酯、酮和砜。转化的范围也已扩展到N-烷基吡啶鎓盐。对于这类底物,在环中存在至少适度吸电子的取代基是获得良好反应性所必需的。特别是,N含有酯基的-烷基吡啶鎓盐在 C-4 位进行区域选择性脱芳构化,而腈和硝基部分导致 C-2 和 C-6 加成产物的非选择性形成。