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Indoloquinazolines functionalized at C-12, which are structural analogs of the natural alkaloid cephalanthrin B, are readily constructed via Ph3 P/I2-mediated one-pot reactions of isatins with aromatic alcohols. In the presence of excess phenols, the C-12 aryloxy ester products are obtained in moderate to good yields under mild conditions. Moreover, fused bicyclic hydroxyaryl derivatives such as 8-hydroxyquinoline give rise to novel C-12 spiro-γ-lactone derivatives. A reactive iminium cation species derived from dehydration of the C-12 hydroxy ester precursor is proposed as the transient intermediate responsible for these transformations. [ABSTRACT FROM AUTHOR]

This review covers article and patent data obtained mostly within the period 2013–2023 on the synthesis and biological activity of quinazolines [ c ]-annelated by five- and six-membered heterocycles. Pyrazolo-, benzimidazo-, triazolo- and pyrimido- [ c ]quinazoline systems have shown multiple potential activities against numerous targets. We highlight that most research efforts are directed to design of anticancer and antibacterial agents of azolo[ c ]quinazoline nature. This review emphases both on the medicinal chemistry aspects of pyrrolo[ c ]-, azolo[ c ]- and azino[ c ]quinazolines and comprehensive synthetic strategies of quinazolines annelated at N(3)–C(4) bond in the perspective of drug development and discovery. [Display omitted] • Pyrrolo[ c ]-, azolo[ c ]- and azino[ c ]quinazolines are overviewed. • Most perspective quinazolines contain amino or aryl/hetaryl moiety at C(2) of the core. • Comprehensive synthetic strategies are analyzed. • [ c ]-Annelated quinazolines demonstrated multiple potential activities against numerous targets. [ABSTRACT FROM AUTHOR]

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.

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 ArN 2 + BF 4 - , that afforded 12-arylindolo[1,2- c ]quinazolin-6(5 H )-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.