New thenoyl-substituted pyrrolo[1,2-c]quinazoline derivatives

Abstract

By the reaction of quinazoline with ω-bromo-2-acethylthiophene in methanol followed by treatment of the intermediate mixture of quaternary salts with unsymmetrical activated alkynes in propenoxide, 3-(2-thienoyl)pyrrolo[1,2-c]quinazoline derivatives were obtained. 3-(2-Thienoyl)-pyrrolo[1,2-c]quinazolines were also obtained by an alternative one-pot procedure directly from quinazoline, ω-bromo-2-acetylthiophene and unsymmetrical activated alkynes in propenoxide, by one-pot, multi-step sequences of reactions. Heating the same mixture of quinazolinium salts in the presence of the strong base 1-(2-thienoyl)-2-(2-thienyl)pyrrolo[1,2-c]quinazoline, an interesting inactivation product of the intermediate quinazolinium-3-thienoylmethylide was obtained.

Synthesis and spectroscopic properties of novel indolizines and azaindolizines

“…The one-pot, three component synthetic procedure has the advantages to avoid preparation and separation of pyrimidinium salts, as well as the formation of the inactivation products, tetrahydrodipyirimido[1,2-b:4,5-b']pyrazine dimmers formed as a results of 3+3 cycloaddition reactions of highly reactive pyrimidinum N-ylides. [58][59][60][61] Scheme 3 -Synthesis of 3-carbonylchromen-2-one substituted indolizine 16.…”

“…[27][28][29][30] Usually, this multistep process starts with the preparation of N-heterocyclic quaternary salts with -halo carbonyl compounds, in situ conversion into corresponding heterocyclic N-ylides in the presence of an inorganic or organic base and 3+2 dipolar cycloaddition reactions of heterocyclic N-ylides with electron-deficient alkynes or alkenes. [31][32][33][34][35][36][37][38][39][40][41][42][43][44][45] Our group has developed a simple one-pot, multicomponent synthetic strategy towards N-bridgehead heterocyclic compounds based on the consecutive quaternization of the N-heteroaromatic compound, in situ generation of the heterocyclic N-ylide, 3+2 dipolar cycloaddition reaction to an electron-deficient alkyne and aromatization sequence, using an epoxide as solvent and acid scavenger. [46][47][48][49][50][51][52][53][54][55] A range of new indolizines and azaindolizines were synthesized via 3+2 dipolar cycloaddition reactions of cycloimmonium ylides, generated from the various N-heterocycles such as pyridine, quinoline, isoquinoline, pyridazine, pyrimidine, phthalazine and benzimidazole derivatives with diverse phenacyl bromides, alkyl bromoacetates, 3-(2-bromoacetyl)-2H-chromen-2-one and electrondeficient alkynes.…”