Visible-Light-Accelerated Pd-Catalyzed Cascade Addition/Cyclization of Arylboronic Acids to γ- and β-Ketodinitriles for the Construction of 3-Cyanopyridines and 3-Cyanopyrrole Analogues
作者:Amitava Rakshit、Prashant Kumar、Tipu Alam、Hirendranath Dhara、Bhisma K. Patel
DOI:10.1021/acs.joc.0c01703
日期:2020.10.2
via a Pd-catalyzed coupling of arylboronic acid with 2-(3-oxo-1,3-diarylpropyl)malononitrile and 2-(2-oxo-2-arylethyl)malononitrile, respectively, under mild reaction conditions, followed by intramolecular cyclization of an intermediate formed after the regeneration of the catalyst under acidic reaction conditions. The cascade reactions proceed in 1,2-dichloroethane solvent under visible-light irradiation
一锅合成策略的2,4,6-三芳基烟腈和2,5-二芳基-1 H-吡咯-3-腈是通过Pd催化的芳基硼酸与2-(3-oxo-1)偶联而完成的,在温和的反应条件下,分别将3-3-二芳基丙基)丙二腈和2-(2-氧代-2-芳基乙基)丙二腈,然后在酸性反应条件下,将催化剂再生后形成的中间体进行分子内环化。级联反应在1,2-二氯乙烷溶剂中在可见光照射下进行,并且在催化量的Pd(OAc)2存在下原位生成活性催化剂和2,2'-联吡啶。活性Pd催化剂借助金属到配体的电荷转移(MLCT)进行光激发,随后芳基硼酸发生氧化还原反金属化,因此无需任何外源光敏剂。以高收率分离出由新的C–C,C–N,C aN和两个新的C═C键组成的目标产物。