[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.
been developed for the synthesis of aromatic and heteroaromatic compounds through tandem allylic substitution/hydroarylative cycloisomerization process. This method provides a facile and general route to substituted benzenes, naphthalenes, other polycyclic aromatics, and various benzene-fused heteroaromatic compounds such as benzofuran, benzothiophene, indole, and carbazoles.
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。
Synthesis of substituted 3-furanoates from MBH-acetates of acetylenic aldehydes via tandem isomerization–deacetylation–cycloisomerization: access to Elliott's alcohol
A new method for the synthesis of 5-substituted furan-3-carboxylates from MoritaâBaylisâHillman acetates of acetylenic aldehydes is reported. The process involves palladium-catalyzed isomerization followed by base-promoted deacetylation and cycloisomerization reactions. The utility of this chemistry is further demonstrated by the synthesis of Elliott's alcohol, a key intermediate of the pyrethroid resmethrins.
An unprecedented copper-catalyzed aminative aza-annulation of enynyl azide using commercially available N-fluorobenzenesulfonhnide (NFSI) as an amination reagent is described. The reaction proceeds via regioselective inter-/intramolecular diamination, incorporating one nitrogen from the NFSI and the other from the azide, to provide amino substituted nicotinate derivatives in a single step with moderate to high yield. This method represents an efficient way to access diverse aminonicotinates through direct C-N bond-coupling processes.