Phosphorus-Carbon Bond Formation: Palladium-Catalyzed Cross-Coupling of H-Phosphinates and Other P(O)H-Containing Compounds

Two generally applicable systems have been developed for the cross-coupling of P(O)H compounds with Csp2X and related partners. Palladium catalysis using a ligand/additive combination, typically either xantphos/ethylene glycol or 1,1-bis(diphenylphosphino)ferrocene/1,2-dimethoxyethane, with diisopropylethylamine as the base, proved to be generally useful for the synthesis of numerous PC containing compounds. Routinely, 2mol% of catalyst are employed (less than half the amount typically employed in most other literature reports). In most cases, excellent results are obtained with a variety of electrophiles (RX, where R=alkenyl, allyl, alkynyl, etc.). The full account of our studies is disclosed, including tandem hydrophosphinylation/coupling and coupling/coupling for doubly catalytic phosphorus-carbon bond formation. The methodology compares favorably with any existing literature report. The use of an additive appears to be a generally useful strategy to control the reactivity of phosphinylidene compounds.