An efficient and selective way to new highly functionalized coronands or spiro derivatives using ultrasonic irradiation

A new, selective, straightforward and general method for preparation of highly functionalized coronands or spiro derivatives bearing 1,2-dihydroxyacetophenone unit, under conventional conditions and ultrasonic irradiation, is reported. The reaction setup involves only one step, acylation of an α-chloro-3,4-dihydroxyacetophenone with phthaloyl dichloride derivatives. 1,3- and 1,4-Phthaloyl dichloride derivatives leads to coronands only, while 1,2-phthaloyl dichlorides lead either to coronands or to spiro derivatives. A feasible explanation for the different behavior between conventional and ultrasound methods could be the different reaction mechanism involved in the two procedures: tetrahedral nucleophilic substitution under conventional conditions and radical substitution under ultrasound. Ultrasound induces a remarkable acceleration of the reactions (from days to minutes) and, most significantly, the yields are twice as high. A feasible explanation for the efficiency of the reactions under ultrasonic irradiation is presented.

A new, selective, straightforward and general method for the preparation of highly functionalized coronands and spiro derivatives bearing the 1,2-dihydroxyacetophenone unit, under conventional conditions and ultrasonic irradiation, is reported.Figure optionsDownload as PowerPoint slideHighlights
► A new method for preparation of coronands or spiro derivatives is reported.
► The reactions took place both under conventional conditions and ultrasound irradiation.
► Ultrasound induces a remarkable acceleration of the reactions and the yields are twice as high.
► A feasible explanation for the efficiency of the reactions under ultrasound irradiation is presented.