Catalytic Asymmetric Hydrophosphination of ortho-Quinone Methides

Abstract

An efficient catalytic asymmetric hydrophosphination of ortho-quinone methides with H-phosphine oxides is established. A chiral bifunctional squaramide is superior to catalyze this enantioselective carbon−phosphorus bond formation, delivering optically active α-arylmethyl phosphine oxides in high yields with high enantioselectivities (up to 94% yield, 99:1 er). Additionally, employing in situ-generated o-QMs for this hydrophosphination step economically provides the corresponding phosphine oxides with comparable yield and enantioselectivity.

Applications of Bifunctional Organocatalysts on ortho‐Quinone Methides

“…Jiang et al . manifested an efficient protocol for enantioselective hydrophosphination reaction of ortho ‐quinone methides with H‐phosphine oxides (Scheme ) . Bifunctional squaramide catalyst was successfully employed in the reaction for the construction of different optically active α ‐arylmethyl phosphine oxides in excellent selectivities.…”

Phenolic 3° Phosphine Oxides as a Class of Metal-Free Catalysts for the Activation of C–O Bonds in Aliphatic Alcohols: Direct Synthesis of Catalyst Candidates, and Kinetic Studies

“…Similarly, the use of PBr 3 and NaH complicates the synthesis of analogs containing nucleophilic or protic functionality. Alternative synthetic approaches to generating 2-HOBPOs include the direct addition of secondary phosphine oxides to ortho-quinone methides (either premade or generated in situ) [15], or by addition of diethyl phosphite, followed by treatment with Grignard reagents, which has previously been used to prepare 2a [16]. However, the most generalizable method appears to be by an addition-rearrangement coupling (ARC) reaction (Figure 5b) [17][18][19].…”

Brønsted acid-mediated tandem cyclization of triarylphosphines and in situ generated ortho-alkynyl quinone methides: access to heterocyclic quaternary phosphonium salts

“…11 Several research groups have taken advantage of this type of reactivity and employed o -QMs as partners in C–P bond constructions, and a variety of P-containing compounds such as 3-phosphinoylbenzofurans and diaryl phosphonates have been prepared. 12 Given the importance of HQPS and our interest in o -QMs chemistry, here, we report a Brønsted acid-mediated tandem P-1,4 addition/intramolecular cyclization reaction. In contrast to the known synthetic method, this tandem approach would enable a fundamentally different synthetic strategy, involving sequential C–P bond formation and heterocycle ring construction with broad functional group–tolerance.…”