Novel pyridine catalysed reactions of dimethyl acetylenedicarboxylate (DMAD) and arylmethylidenemalononitriles: a stereoselective synthesis of highly substituted buta-1,3-dienes

Synthesis of new stable crystalline zwitterionic products from the reactions of 1-methylimidazole, acetylenic esters and strong cyclic CH-acids

The reactive 1:1 intermediate produced in the reaction between 1-methyl imidazole and dialkyl acetylenedicarboxylates was trapped by strong cyclic CH-acids such as N,N′-dimethylbarbituric acid, Meldrum's acid, cyclohexan-1, 3-dione, indan-1,3-dione, cyclopentan-1,3-dione and tetronic acid to yield stable 1,4-diionic imidazolium betaines in excellent yields.

A Facile and Diastereoselective access to Functionalised Benzopyrano[3,4-a] Quinolizines via a Pyridine-Based Three-Component Reaction

The reaction of 2-oxo-2 H-chromene-3-carbonitriles with dialkyl acetylenedicarboxylates and pyridines results in a three-component condensation reaction in which the 2-oxo-2 H-chromene-3-carbonitrile group acts as a dipolarophile to produce benzopyrano[3,4- a] quinolizines under mild conditions in good yield.

Engaging the Pyridine-DMAD Zwitterion in a Novel Strategy for the Selective Synthesis of Highly Substituted Benzene and Cyclopentenedione Derivatives

[reaction: see text] The pyridine-mediated reaction of dimethyl acetylenedicarboxylate and cyclobutene-1,2-diones affords selective access to either hexasubstituted benzene derivatives or cyclopentenedione derivatives depending on the concentration of pyridine.

Pyridine-Catalyzed Addition of Diaryl-1,2-diones to Dimethyl Butynedioate Leading to the Formation of 1,2-Diaroyl Dimethyl Maleates via an Unprecedented Rearrangement

[reaction: see text] Pyridine catalyzes the reaction of 1,2-diaryl diones with dimethyl butynedioate to afford diaroyl maleates. This unprecedented rearrangement involves a unique benzoyl migration and proceeds with complete stereoselectivity.