Synthesis of 1-aryl-2,3-diaroyl cyclopropanes from 1,3,5-triaryl-1,5-diketones and their transformation into E,E-1,4-diaryl-1,3-butadienes

A new method for the synthesis of 1-aryl-2,3-diaroyl cyclopropanes has been developed by iodine/DBU-mediated cyclization of 1,3,5-triaryl-1,5-diketones. The alcohols derived by the reduction of these cyclopropanes, when treated with conc. HCl, afforded a series of 1,3-dienes through cyclopropyl ring-opening and subsequent fragmentation. Overall, the synthetic sequence represents a new non-Wittig methodology for the synthesis of 1,3-dienes from 1,5-diketones.

One-Pot Synthesis of 1,5-Diketones under a Transition-Metal-Free Condition: Application in the Synthesis of 2,4,6-Triaryl Pyridine Derivatives

We developed a facile and green one-pot synthetic method for substituted 1,3,5-triaryl-1,5-diketones by Claisen-Schmidt condensation following Michael addition reaction of aryl ketones and aryl aldehydes under a transition-metal-free condition. This convenient one-pot synthetic strategy has several advantages, including being transition-metal-free, having no extra additives or reagents, having a broad substrate scope, having a high isolated yield, having a minimum amount of base employment, having a shorter reaction time, use of cheap starting materials, cost-effectiveness, and being environment friendly. Some of the chemical structures of 1,5-diketones were confirmed by X-ray single-crystal diffraction analysis. The application of 1,5-diketones was demonstrated in the preparation of 2,4,6-triaryl pyridine derivatives under a catalyst-free system using ammonium acetate as a nitrogen source.

A facile one pot synthesis of thiazolo[3,2-a]benzimidazole and pyran fused polyheterocyclic scaffolds

An efficient synthesis of dihydro-4H-benzo[4,5]imidazo[2,1-b]pyrano[2,3-d]thiazole by a multicomponent route starting from 2-((1H-benzo[d]imidazol-2-yl)thio)-1-phenylethan-1-one, an aromatic aldehyde and malononitrile is described. This protocol features a metal free approach with good substrate scope and decent yield. The heterocyclic skeleton obtained in this study may have interesting biological properties.

Thio-Michael addition of thioamides and allenes for the selective construction of polysubstituted 2-arylthiophenes via TBAI/H2O2 promoted tandem oxidative annulation and 1,2-sulfur migration

A novel TBAI-catalyzed tandem thio-Michael addition/oxidative annulation of allenes and thioamides for the construction of polysubstituted 2-arylthiophenes under a sulfur migration transformation protocol has been developed. The transition-metal-free protocol achieves the oxidative cyclization reaction of thioamides containing electron-rich substituents with allenes to construct polysubstituted thiophenes selectively by controlling oxidation conditions.