AbstractA copper‐catalyzed dearomative alkynylation of pyridines is reported with excellent regio‐ and enantioselectivities. The synthetically valuable enantioenriched 2‐alkynyl‐1,2‐dihydropyridine products afforded are generated from the readily available feedstock, pyridine, and commercially available terminal alkynes. The three‐component reaction between a pyridine, a terminal alkyne, and methyl chloroformate employs copper chloride and StackPhos, a chiral biaryl P,N‐ ligand, as the catalytic system. Under mild reaction conditions, the desired 1,2‐addition products are delivered in up to 99 % yield with regioselectivity ratios up to 25 : 1 and enantioselectivities values of up to 99 % ee. Activated and non‐activated terminal alkynes containing a wide range of functional groups are well tolerated. Even acetylene gas delivered mono‐alkynylated products in high yield and ee. Application of the methodology in an efficient enantioselective synthesis of the chiral piperidine indolizidine, coniceine, is reported.
摘要 铜催化的吡啶脱芳基炔化反应具有极佳的区域和对映选择性。从现成的原料吡啶和市场上可买到的末端炔烃中生成了具有合成价值的对映体富集的 2-炔基-1,2-二氢吡啶产物。吡啶、末端炔烃和氯甲酸甲酯之间的三组分反应采用氯化铜和手性双芳基 P,N- 配体 StackPhos 作为催化体系。在温和的反应条件下,所需的 1,2-加成产物的产率高达 99%,区域选择性比高达 25 :1 ,对映体选择性高达 99 % ee。含有多种官能团的活化和非活化末端炔烃都能很好地耐受。即使是乙炔气也能以高产率和高ee值提供单炔基化产物。报告还介绍了该方法在手性哌啶吲哚利嗪--康尼辛--的高效对映选择性合成中的应用。