Direct and Enantioselective Vinylogous Michael Addition of α-Alkylidenepyrazolinones to Nitroolefins Catalyzed by Dual<i>Cinchona</i>Alkaloid Thioureas
作者:Gloria Rassu、Vincenzo Zambrano、Luigi Pinna、Claudio Curti、Lucia Battistini、Andrea Sartori、Giorgio Pelosi、Giovanni Casiraghi、Franca Zanardi
DOI:10.1002/adsc.201300964
日期:2014.7.7
pyrazolinones at the α‐position relying on nucleophilic addition or annulation procedures, use of α‐alkylidene electron‐rich analogues in asymmetric vinylogous coupling to carbon electrophiles is substantially an uncharted domain. We now report, for the first time, that alkylidenepyrazolinones carrying an enolizable carbon at the γ‐position efficiently participate in direct and asymmetric, catalytic vinylogous
虽然存在几种依赖于亲核加成或成环程序在吡咯啉酮类化合物在α位进行不对称官能化的协议,但在不对称乙烯基键合至碳亲电试剂的过程中使用α-亚烷基富电子类似物基本上是一个未知领域。现在,我们首次报道,在γ位带有可烯丙基碳的亚烷基吡唑啉酮有效地参与了对硝基烯烃的直接和不对称催化乙烯基迈克尔型加成反应,从而以高收率提供了预期的加合物,并具有完整的γ位置选择性和具有极高的对映,非对映和几何选择性。两种对映体加合物均采用准均等地获得对映体奎宁或奎尼丁基硫脲催化剂对。