Efficient synthesis of tetra- and penta-substituted benzenes via a domino annulation reaction of a pyridinium ylide and chalcone o-enolate

Abstract

A very simple and high efficient synthetic protocol for tetra- and penta-substituted benzene derivatives has been provided by tetramethylguanidine (TMD) promoted reaction of 4-(N,N-dimethylamino)-1-phenacyl-pyridinium bromide with chalcone o-enolates in DMF...

Molecular diversity of the base-promoted reaction of phenacylmalononitriles with dialkyl but-2-ynedioates

“…Recently, Zhang and Ban reported a NaHCO 3 -promoted reaction of phenacylmalononitriles and N-alkylmaleimides to give the novel cyclopenta[c]pyrrole-4-carboxamides with unprecedented rearrangement of the alkyl group [34] (reaction 4 in Scheme 1). Inspired by these novel reactions and in continuation of our aim to develop domino reactions of electron-deficient alkynes [35][36][37][38][39][40][41][42][43][44][45][46][47][48][49][50], we have investigated the base-promoted reactions between phenacylmalononitriles and dialkyl but-2-ynedioates. Here we wish to report the selective synthesis of cyclopent-1-ene-1,2dicarboxylates and complex carboxamide-bridged dicyclopentene derivatives in good yields and with high diastereoselectivity (reaction 5 in Scheme 1).…”

Synthesis of 1,2,4,5-tetra-substituted benzenes via copper-catalyzed dimerization of γ,δ-unsaturated ketones

“…9,10 Simultaneously, successive annulation reactions between pyridinium ylides and chalcones o -enolates could also furnish poly-substituted benzenes (Scheme 1b(IV)). 11 Despite fruitful results in the synthesis of the 1,2,4,5-tetra-substituted benzenes, undesired limitations in the pre-synthesis of benzene and poor atom-economy remain considerable. Meanwhile, more facile, efficient and highly atom-economical synthetic methods for the construction of the 1,2,4,5-tetra-substituted benzenes still need to be expanded.…”