A Calixarene‐Decorated Phosphole Oxide

Abstract

A conical calix[4]arene receptor equipped with a benzo[ b ]phosphole oxide grafted to its upper rim was obtained in six steps by starting from 5‐bromo‐25,26,27,28‐tetrapropyloxycalix[4]arene. The route involved the synthesis of the calixarene intermediate 5 that bears a 2‐(diphenylphosphinyl)phenylethynyl substituent connected to the calixarene wider rim. Under Pd II /Cu I co‐catalysis, mixed phosphane‐alkyne 5 , when heated at 120 °C, underwent P–Ph bond cleavage followed by attack of the phosphorus atom onto the carbon–carbon triple bond. The resulting calixarene‐phosphole was then oxidised to form the corresponding phosphole oxide 9 . Compound 9 luminesces strongly under UV irradiation. The solid‐state structure of a derivative of phosphane‐alkyne 5 , AuCl complex 8 , was established by a single‐crystal X‐ray diffraction study.