Base-promoted decarboxylative condensation of cinnamonitriles and phenylacetic acids with sulfur: direct access to azatrithiapentalenes

We report herein a one-step three-component decarboxylative strategy for the construction of novel azatrithiapentalenes from readily available cinnamonitriles, arylacetic acids and elemental sulfur. The reaction was found to proceed in DMSO in the presence of DABCO as a basic promoter through an unusual disproportionate incorporation of three sulfur atoms into the carbon skeletons derived from two organic substrates. A comprehensive examination of the substrate scope demonstrated that the reaction conditions are broadly tolerant, including substrates bearing a diverse array of substituents with markedly different electronic and steric features. Control experiments demonstrated that elemental sulfur reacts independently with both starting organic substrates to yield two key intermediates that could combine together to yield azatrithiapentalenes. The reaction could be extended to phenylmethanethiols or dibenzyl disulfides in place of phenylacetic acids.