Brønsted acid-catalyzed 1,6-hydrophosphination of propargylic para-quinone methides and aza-para-quinone methides for the rapid construction of phosphorus-substituted quaternary carbon centers
Ting Xiong, Hao Yuan, Fuxing Yang, Jun Jiang
Abstract
An intriguing Brønsted acid-catalyzed 1,6-hydrophosphination of in situ generated propargylic para-quinone methides (p-QMs) and aza-para-quinone methides (aza-p-QMs) with H-phosphorus oxides via dehydration/1,6-addition under ultrasonic irradiation is described. This methodology provides a rapid and green approach for the construction of diarylmethyl phosphorus oxides bearing phosphorus-substituted quaternary carbon centers in high yields (up to 98% yield) within merely 5 min. This environmentally benign protocol represents a unique example of 1,6-conjugate additions of propargylic p-QMs and aza-p-QMs for site-selective C–P bond formation in an operationally simple and atom-economical manner. The use of readily available Brønsted acid catalyst, operationally simplicity, high yields, and high atom economy make this protocol very facile, practical, easily scaled-up and environmentally friendly.