I2-Mediated Site-Selective C-H Functionalization: Access to p-Amino-Substituted Unsymmetrical Benzils and Quinoxalines from Sulfoxonium Ylides.

An I2-mediated approach for selective C-H functionalization of unprotected aniline derivatives for synthesizing benzils and quinoxaline derivatives from sulfoxonium ylides has been described. Aniline derivatives and sulfoxonium ylides ornamented with different functional groups showed good compatibility. They afforded the corresponding products with moderate to high yields via a mild and simple procedure. Finally, we validated the practicality of this method by scaling up the reaction and further conversion of the synthesized derivatives into other valuable molecules.

Elemental Sulfur-Mediated Synthesis of Quinoxalines from Sulfoxonium Ylides.

A novel straightforward and catalyst-free approach for synthesizing quinoxaline derivatives from sulfoxonium ylides and o-phenylenediamines mediated by elemental sulfur has been described. Due to the simple and mild reaction conditions, the sulfoxonium ylides and o-phenylenediamines decorated with different functional groups furnished moderate to high yields of quinoxaline derivatives and were well tolerated. Finally, large-scale reactions, the synthesis of pyrazines, and some bioactive compounds are used to illustrate the potential utility of the developed approach.

Metal-Free Syntheses of α-Ketothioamide and α-Ketoamide Derivatives from Sulfoxonium Ylides.

An efficient base, additive and metal-free synthetic methods for α-ketothioamide and α-ketoamide derivatives from readily available sulfoxonium ylides have been described. Sulfoxonium ylides with primary or secondary amines afforded α-ketothioamides in the presence of elemental sulfur, whereas α-ketoamides were produced when I2 and TBHP were present. The reaction proceeded well at room temperature and generated the corresponding molecules in good to excellent yields. The reaction can be scaled-up and tolerated by a range of functional groups with simple operational procedures.

Introducing tetramethylurea as a new methylene precursor: a microwave-assisted RuCl3-catalyzed cross dehydrogenative coupling approach to bis(indolyl)methanes.

Herein we report a microwave assisted Ru(iii)/TBHP-mediated reaction of indoles with tetramethylurea (TMU) synthesizing symmetrical as well as unsymmetrical bis(indolyl)methanes, where TMU acts as a methylenating agent. This is the first report where TMU is used as a methylene source. Moreover, the synthesis of unsymmetrical bis(indolyl)methanes by using a carbon precursor is also reported herein for the first time. Various substituted indoles are used for the reaction. The reaction is high yielding and takes a much shorter time to accomplish compared to the existing methods.