[4 + 2]-Annulation of MBH-Acetates of Acetylenic Aldehydes with Imidazoles/Benzimidazoles To Access Imidazo[1,2-<i>a</i>]pyridines/Benzimidazo[1,2-<i>a</i>]pyridines
作者:Chada Raji Reddy、Amarender Goud Burra
DOI:10.1021/acs.joc.9b01118
日期:2019.7.19
developed to construct diversely substituted imidazo[1,2-a]pyridines and benzimidazo[1,2-a]pyridines in good to excellent yield. The advantage of this unique [4 + 2]-annulation lies in the employment of readily accessible starting materials, Morita–Baylis–Hillman acetates of acetylenic aldehydes as C4 synthons, and simple imidazoles or benzimidazoles as C2 synthons.
A new protocol has been developed for the synthesis of substituted thiophenes under mild and metal-free reaction conditions via the base-promoted thioannulation of Morita–Baylis–Hillman acetates of acetylenic aldehydes with potassium thioacetate involving a tandem allylic substitution/deacetylative 5-exo-dig-thiocycloisomerization. The obtained products provide an entry to 4H-thieno[3,2-c]chromene
已开发出一种新的方案,用于在温和且无金属的反应条件下,通过Morita-Baylis-Hillman乙炔醛乙酸盐与硫代乙酸钾的碱促进硫代环化反应,合成串联噻吩取代/去乙酰化5-exo-挖-硫代环异构化。所获得的产物提供了4 H-噻吩并[3,2- c ]亚甲基和噻吩并[3,2- c ]二氢喹啉的入口。