Pd-Catalyzed Cross-Coupling Reactions Promoted by Biaryl Phosphorinane Ligands

Abstract

We report the use of biaryl phosphorinanes as ligands for Pd-catalyzed cross-coupling reactions. A modular synthesis was developed that employs a double conjugate addition of primary biaryl phosphines into 1,1,5,5-tetraalkyl penta-1,4-diene-3-ones. Notably, this synthesis does not require the use of copper, a known contaminant in structurally related biaryl phosphane ligands. Using the synthetic strategy described above, we synthesized a library of biaryl phosphorinanes, varying their substitution about phosphorus and the steric and electronic nature of the biaryl motif. We then benchmarked their performance as ligands in Pd-catalyzed cross coupling reactions such as aryl sulfonamidation, aryl alkoxylation, and aryl amination in the presence of soluble organic bases. In each reaction studied, many ligands outperformed biaryl phosphanes known to promote the given transformation. Detailed substrate scopes were determined using high-throughput screening technology. Several biaryl phosphorinanes and their cor...