无配体的铜催化的[3 + 2]环化反应,用于合成吡咯并[1,2- a ]喹啉,其中环境空气为末端氧化剂†
摘要:
2-(喹啉-2-基)乙酸乙酯,2-(异喹啉-1-基)乙酸乙酯和2-吡啶-2-基乙酸乙酯的无配体Cu催化的[3 + 2]环加成反应已经开发了具有(E)-查耳酮的“一锅”合成吡咯并[1,2- a ]喹啉,吡咯并[ 2,1- a ]异喹啉和吲哚嗪。在温和条件下,以空气为唯一氧化剂,以中等至良好的收率分离出环化产物。
A transition metal-free iodinecatalyzedsynthesis of indolizine derivatives through [3+2] cyclization of 2-pyridylesters and chalcones has been described. The method is efficient to synthesize a variety of substituted indolizines including hetero aromatic indolizines. Mechanistic studies reveal that, the reaction follows the radical pathway.
Synthesis of indolizine-1-carboxylates through the Ortoleva-King reaction of 2-pyridylacetate followed by the Aldol condensation under mild reaction conditions has been described. This protocol is compatible with a broad range of functional groups, and it has been also successfully extended to unsaturated ketones, bringing about the regioselective formation of benzoyl-substituted indolizines through Michael addition followed by C-N bond formation, which are difficult to prepare by previous methods in a single step.
NUGENT R. A.; MURPHY M., J. ORG. CHEM., 52,(1987) N 11, 2206-2208