Four‐Component Synthesis of Phosphonium Salts: Application Toward an Alternative Approach to Cross‐Coupling for the Synthesis of Bis‐Heteroarenes

Abstract

As eries of stable phosphonium salts have been synthesized via an ovel four-component reaction of an arene nucleophile,2 -heteroatom substituted aryl aldehyde,a nd phosphine in presence of an acid. The phosphonium salts thus obtained were utilized for the synthesis of avariety of bisheteroarenes,p roviding an efficient alternative method to the classical cross-coupling strategies.Scheme 2. Proposed retrosynthetic approach for the synthesis of bisheteroarenes.

DMSO-Promoted Difluoroalkylation of Organophosphonium Salts with Difluoroenol Silyl Ethers

“…26 Despite its apparent synthetic simplicity and predictability, difficulties related to restraining the generation of undesired ylides are foreseeable. 27 To test our design, we initially treated diarylmethyl triphenylphosphonium salt 1a with ((2,2-difluoro-1phenylvinyl)oxy)trimethylsilane (2a) in DMSO at 50 °C under air for 12 h, which led to the production of the difluoroalkylated product 3aa in a 55% isolated yield (Table 1, entry 1; see the Supporting Information for more details). However, increasing the reaction temperature to 80 or 110 °C only gave rise to the corresponding product 3aa in a 35% or 36% yield, respectively (Table 1, entry 2 or 3, respectively).…”