PPh₃-Mediated One-Pot Synthesis of Functionalised 4-oxo-4H-benzo[4,5]imidazo[1,2,a]pyrimidines

Abstract

A one-pot synthesis of 4-oxo-4H-benzo [4,5]imidazo[1,2,a]pyrimidines from dialkyl acetylenedicarboxylates and methyl benzimidazole-2-yl carbamate in the presence of triphenylphosphine is described.Scheme 1 Reaction of methyl benzimidazole-2-yl carbamate and dialkyl acetylenedicarboxylates in the presence of triphenylphosphine.

Coumarin: A Valid Scaffold in Medicinal Chemistry

“…In the early 1900s, the Knoevenagel reaction emerged as an important synthetic method to synthesize coumarin derivatives with carboxyl group at the 3-position [19,20]. Many other synthetic methods for coumarins have been reported, including the Pechmann [21], Reformatsky [22], Perkin [23], Kostanecki-Robinson synthesis [24] and Wittig reactions [25]. The general schemes for synthesis of coumarin by various methods are shown in fig.…”

A Multifield Study on Dimethyl Acetylenedicarboxylate: A Reagent Able to Build a New Cycle on Diaminoimidazoles

“…In a first step, an addition ofDMAD at the multiple bond by the amino or mercapto group of the starting triazole occurs, then an intramolecular cyclization on the NH fragment due to the “far” ester group happens. A similar process, involving N -substituted aminotriazoles 6 , [ 25 ] aminoimidazoles 7 and 10 , [ 26 , 27 ] aminopyrazoles 3 , [ 28 ] 2-amino-3-carboethoxyindoles 12b [ 29 ], and indoline-2-thiones 12a [ 30 ] leads to the formation of [1,2,4]triazolo[4,3- a ]pyrimidinones 8 , imidazo[1,2- a ]pyrimidinones 9 and 11 , pyrazolo[1,5- a ]pyrimidinones 5 , pyrimido[3,2- a ]indolones 14 , and thiopyrano[2,3- b ]indolones 13 .…”

Three-Component Reaction Between Indan-1,2,3-trione2-Oxime and Acetylenic Esters in the Presence of Triphenylphosphine

“…N-Heterocycles receive considerable attention in the literature as a consequence of their exciting biological properties and their role as pharmacophores 7 . In continues of our previous works on the reaction between phosphorus nucleophiles and acetylenic esters in the presence of organic acids [8][9][10][11][12][13][14][15][16] . We decided to investigate the reaction of OH-acidic compound such as indan-1,2,3-trione 2-oxime 1 with acetylenic esters in the presence of triphenylphosphine.…”