Elemental Sulfur‐Promoted Aerobic Cyclization of Ketones and Aliphatic Amines for Synthesis of Tetrasubstituted Imidazoles

Abstract

Elemental sulfur‐promoted cyclization for the one‐pot synthesis of tetra‐substituted imidazoles from benzylamines and ketones is described. Elemental sulfur combined with molecular oxygen as the benign co‐oxidant was found to be the key for the high efficiency of this transformation under metal‐free conditions. A range of tetrasubstituted imidazoles were synthesized from simple ketones and amines with good functional group tolerance.magnified image

S8-Catalyzed triple cleavage of bromodifluoro compounds for the assembly of N-containing heterocycles

“…Combined with the above experimental observations and previous reports,12 the mechanism of S 8 -catalysed triple cleavage of halogenated difluoro compounds is proposed in Scheme 6. Deprotonation of sulfydryl of reactant 1 followed by nucleophilic attack on S 8 affords the ring-opened sulfanyl anion I .…”

Recent Advances in the Synthesis of Heterocycles via Reactions Involving Elemental Sulfur

“…In 2018, Huang and Deng et al reported a convenient multicomponent access to tetrasubstituted imidazoles 342 from oxidative condensation of enolizable ketones 341 with two molecules of aliphatic amines (Scheme 122). [148] This reaction involved both sulfur (1 equiv.) and oxygen (1 atm) as oxidants.…”

New synthesis of 2-aroylbenzothiazoles via metal-free domino transformations of anilines, acetophenones, and elemental sulfur

“…23 Furthermore, elemental sulfur-catalyzed/mediated synthetic strategies have been studied. [24][25][26] A large number of organosulfur compounds have been generated by employing different pathways in the presence of elemental sulfur. [27][28][29][30] Multicomponent reactions have emerged as a straightforward approach to prepare estimable complex organic compounds from simple reactants, affording considerable advantages over traditional multistep reaction sequences.…”