FERRIER REARRANGEMENT UNDER NONACIDIC CONDITIONS BASED ON IODONIUM-INDUCED REARRANGEMENTS OF ALLYLIC N-PENTENYL ESTERS, N-PENTENYL GLYCOSIDES, AND PHENYL THIOGLYCOSIDES

摘要

Iodonium-promoted rearrangements of easily accessible allylic n-pentenyl esters, n-pentenyl glycosides, or phenyl thioglycosides result in the generation of the allylic oxocarbenium ion intermediate II of the Ferrier rearrangement, I --> II --> IIIa, of glycals leading to 2,3-unsaturated glycosides. Thus the Ferrier rearrangement can now be carried out under nonacidic conditions, with NIS or iodonium dicollidinium perchlorate as promoter, to afford good yields of disaccharides in which acid-labile functionalities, either in the glycosyl donor or glycosyl acceptor, have been preserved. [References: 74]