Acid‐Catalyzed Regioselective Synthesis of α‐Diarylmethyl Substituted Phenols and para‐Quinone Methides in Water

Abstract

A facile and efficient method for the synthesis of αdiarylmethyl substituted phenols from para-quinone methides (p-QMs) with phenols has been developed by using phosphoric acid as the catalyst and water as the green solvent under mild conditions. In addition, when TEMPO was added as an additive for the reaction, the diaryl-substituted para-quinone methides could be generated as the target product. The reactions show high functional group tolerance, good to excellent yields and unique selectivity, and a broad range of α-diarylmethyl motif containing phenol(s) and quinones could be prepared through the divergent methods. Furthermore, a series of control experiments were performed to gain the insights of the plausible mechanisms. These protocols have a high atomic economy, and may have significant implications for the construction of C(sp 3 )À C(sp 2 ) bonds in organic synthesis.

Csp2–H functionalization of phenols: an effective access route to valuable materials via Csp2–C bond formation

“…Enantioselective investigations with a chiral Brønsted acid resulted in an 80 : 20 enantiomeric ratio (Scheme 24). 90 W. Li, P. Li et al developed an organocatalytic enantioselective conjugate addition of 2-naphthols to ortho-hydroxyphenyl substituted para-quinone methides. A series of enantioenriched triarylmethanes were obtained in good to excellent yields under mild reaction conditions (Scheme 25).…”

“…Enantioselective investigations with a chiral Brønsted acid resulted in an 80 : 20 enantiomeric ratio ( Scheme 24 ). 90 …”