Synthesis of indolo[1,2-c]quinazolines from 2-alkynylaniline derivatives through Pd-catalyzed indole formation/cyclization with N,N-dimethylformamide dimethyl acetal

Abstract

An efficient strategy for the synthesis of 6-unsubstituted indolo[1,2-c]quinazolines is described. The Pd-catalyzed reaction of o-(o-aminophenylethynyl) trifluoroacetanilides with Ar–B(OH)2 afforded 2-(o-aminophenyl)-3-arylindoles, that were converted to 12-arylindolo[1,2-c]quinazolines by adding dimethylformamide dimethyl acetal (DMFDMA) to the reaction mixture after extractive work-up. This reaction outcome is different from the previously reported Pd-catalyzed sequential reaction of the same substrates with Ar–I, Ar–Br and ArN2 +BF4 −, that afforded 12-arylindolo[1,2-c]quinazolin-6(5H)-ones. Moreover, 12-unsubstituted indolo[1,2-c]quinazolines can be obtained both by reacting 2-(o-aminophenyl)indoles with DMFDMA or by sequential Pd-catalyzed reaction of o-(o-aminophenylethynyl)aniline with DMFDMA.

Study of methylation reactions of 2-phenylquinazoline-4-tion with “soft” and “hard” methylation agents and determination of its biological activity

“…In the mixture to the solution (suspension), 0,001 mole of NaH was added and mixed again for 30 minutes. 0.01 mole of methylation agent methyl iodide or dimethyl sulfate, 5ml of methyltosylates in the corresponding solution is added dripping to the solution the solution (suspension) of the formed salt [1,[7][8]. The reaction mixture was stirred at room temperature for 24 hours or heated in a water bath for 4 hours.…”

“…About 80% of them are carbon, H, O, N, S, P and halogens. The unique feature of the carbon atom, such as its ability to combine not only with other elements, but also with each other to form long straight and branched chains, various rings and carcass structures that makes it possible to synthesize innumerable compounds [3][4]8]. This, in turn, leads to the search for compounds with different properties among the synthesized substances and their successful application in the economic sectors, such as medicine, agriculture, food and light industry.…”

Applications of Ethynylanilines as Substrates for Construction of Indoles and Indole‐Substituted Derivatives

“…In 2018, Benaissa Boubia et al [33] have described the microwave assisted synthesis of novel indole sulphonamide derivatives 55 (Scheme 18) from 54. [34] The starting material 54 can be synthesized as shown in the below scheme. The optimized reaction conditions disclosed that cyclization of alkynes take place in the presence of copper acetate and microwave at 130-140°C temperature.…”

“…Later in the same year palladium catalysed strategy for synthesis of fused 6-unsubstituted Indolo [1,2-c] quinazolines 82 has been described by Fabio Marinelli et al [47] (Scheme 27) from o-(oaminophenylethynyl) trifluoroacetamide's 79 by treating with several aryl boronic acids (ArÀ B(OH) 2 ). The reaction follows 2 steps strategy which includes cyclization of o-(oaminophenylethynyl) trifluoroacetamide's to the corresponding 2-(o-aminophenyl)-3-arylindole derivatives 80, followed by subsequent annulation under the reaction of dimethylformamide dimethyl acetal (DMFDMA) to afford desired 12arylindolo[1,2-c] quinazolines 81 in moderate to good yields.…”

“…In 2018, Benaissa Boubia et al [33] . have described the microwave assisted synthesis of novel indole sulphonamide derivatives 55 (Scheme 18) from 54 [34] . The starting material 54 can be synthesized as shown in the below scheme.…”