Palladium-Catalyzed Cross-Coupling of H-Phosphinate Esters with Chloroarenes

Abstract

The palladium-catalyzed cross-coupling reaction between H-phosphinate esters and chloroarenes or chloroheteroarenes is described. This reaction is the first general metal-catalyzed phosphorus-carbon bond-forming reaction between a phosphorus nucleophile and chloroarenes.

The Palladium Acetate‐Catalyzed Microwave‐Assisted Hirao Reaction without an Added Phosphorus Ligand as a “Green” Protocol: A Quantum Chemical Study on the Mechanism

“…The generally accepted catalytic cycle for the Pd(0)‐catalyzed Hirao reaction is shown in Figure . According to this protocol, the main steps are the oxidative addition of the aryl halide to the Pd(0) complex ( I ) to give Pd(II) complex II , the change of ligands that leads to key intermediate III , and the reductive elimination providing the product [ArP(O)Y 2 ], and regenerating the Pd(0) catalyst …”

“…As a matter of fact, a few refinements of the above cycle were also proposed by several authors. One such is the incorporation of the P(III) tautomeric form of the >P(O)H species in the primary Pd‐adduct ( II ) forming intermediate IV that undergoes a deprotonation by the base present in the mixture to afford the secondary Pd‐adduct ( III′ / III ) (Scheme ) ,,…”

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

“…As a result, intense research has been devoted to this topic in recent years 2. Over the past decade, our laboratory has reported various synthetic methodologies for the preparation of H ‐phosphinates and disubstituted phosphinates,3 and we recently disclosed the first general PC bond formation using the palladium‐catalyzed reaction of H ‐phosphinates with aryl chlorides 4. Below, we are reporting the full account of our studies concerning the palladium‐catalyzed cross‐coupling of P(O)H compounds with C sp2 and related electrophiles.…”

“…More recently, our focus shifted to H ‐phosphinates 4,15. Various examples of functionalization of R 1 P(O)(OR)H through cross‐coupling have been reported in the literature,11 however, our 2011 communication was the first to offer a general method in which aryl chlorides could be employed, using a broadly applicable set of conditions, lower catalyst loadings, and the use of additives like ethylene glycol (EG) 4. Following this work, we have continued our efforts to develop a synthetic method as generally applicable as possible to any P(O)H reagent, especially H ‐phosphinates, but also H ‐phosphonates, and secondary phosphine oxides.…”

“…But the study proved that EG could be a general solution for the synthesis of phosphinates R 1 P(O)(OR)Ar, even with aryl chlorides. Dimethoxyethane (DME) and propylene glycol (PG) were also identified as other promising additives 4…”