Efficient one-pot synthesis of 2-oxo-1,9a-dihydro-2H-pyrido[1,2-a]pyrimidine derivatives

One‐pot Two‐Step Cycloaddition Reaction for Convenient Synthesis of Polycyclic Spirooxindole‐fused [1,3]Oxazines

“…It has been reported that the three-component reactions of pyridine and N-alkylisatins with dimethyl acetylenedicarboxylate in 1,2-dimethoxyethane (DME) at room temperature afforded 1, [46,47] in high yields and with a ratio of two diastereoisomers in a range of 5∶1 to 7∶1. Thus, we wanted to combine this three-component reaction with the sequential DielsAlder reaction into a one-pot domino reaction.…”

“…[41][42][43][44][45] In order to explain the formation mechanism of spirooxindoline fused [1,3]oxazines, a domino reaction path was proposed in Scheme 2 based on the reported Huisgen's 1,4-dipolar addition reaction and Diels-Alder reaction. [46][47][48][49][50] At first, addition of substituted pyridine to electron-deficient alkynes gave a Huisgen's 1,4-dipole intermediate (A). Secondly, addition of Huisgen's 1,3-dipole (A) to 3-carbonyl group of isatin afforded the intermediate (B).…”

One-pot reductive N-vinylation and C(4)-phosphorylation of pyridines with alkyl propiolates and secondary phosphine chalcogenides

“…It is noteworthy that the vast majority of known reactions involving the generation of zwitterionic species by the addition of pyridine to electron-deficient acetylenes and their further intramolecular transformation 12 or interception by electrophiles (possessing activated C-C double or triple bonds, 13 carbonyl 14 or isocyanate groups, 15 and acidic CH-, 16 NH-17 or PH-10 functional groups) leads to selective formation of 1,2-dihydropyridines.…”

A facile and efficient addition reaction of nitrogen‐containing heterocyclic compounds with DMAD under neat conditions

“…Many works have been reported on the reactions of dimethyl acetylenedicarboxylate (DMAD) with nitrogen‐containing heterocyclic compounds, which led to a number of interesting carbon–carbon bond‐forming reactions and heterocyclic constructions [16–21]. However, most of these involved in dry solvents, long reaction times, and difficult isolations.…”