Conjugate Addition Reactions of <i>N</i>-Carbamoyl-4-pyridones and 2,3-Dihydropyridones with Grignard Reagents in the Absence of Cu(I) Salts
作者:Fenghai Guo、Ramesh C. Dhakal、R. Karl Dieter
DOI:10.1021/jo400936z
日期:2013.9.6
4-addition reactions with Grignard reagents in the presence of chlorotrimethylsilane (TMSCl) or BF3·Et2O in excellent yields. Copper catalysis is not required, and mechanistic considerations suggest that the reaction is proceeding by a conjugate addition pathway rather than by a pathway involving 1,2-addition to an intermediate pyridinium ion. TMSCl-mediated conjugate addition of Grignard reagents to 2-substituted-2
在氯代三甲基硅烷(TMSCl)或BF 3 ·Et 2 O存在下,N -Boc-和N-乙氧基羰基-4-吡啶酮以及所得的2,3-二氢吡啶酮与格氏试剂进行1,4-加成反应,收率很高。不需要铜催化,并且机理上的考虑表明反应是通过共轭加成途径而不是通过涉及向中间体吡啶鎓离子进行1,2-加成的途径进行的。TMSC1介导的格氏试剂与2-取代的2,3-二氢吡啶酮的共轭加成立体选择性地产生反式-2,6-二取代的哌啶子酮,而铜酸盐试剂则产生反式或顺式非对映异构体或混合物。