O. Middel et al., The first lateral functionalization of calix[4]arenes by a homologous anionic ortho-Fries rearrangement, J ORG CHEM, 65(3), 2000, pp. 667-675
Treatment of calix[4]arene bis-O-carbamates 4a,b-6a,b with LDA in THF resul
ts in the regio-and stereoselective introduction of both axial and equatori
al carboxamide groups at the methylene bridges via a homologous anionic ort
ho-Fries rearrangement to give 7-16. The stereochemical outcome of the rear
rangement is dependent on the reaction conditions and the conformation of t
he starting material. Stereochemical and structural proof has been secured
by the X-ray crystal structure of calix[4]arene 10 having only one equatori
al carboxamide moiety. The use of this novel class of methylene bridge-func
tionalized calix[4]arenes is illustrated by the formation of bis-gamma-lact
one 19, while the enhanced acidity of the remaining hydroxyl groups, owing
to the presence of axial carboxamide groups at the methine bridges, followe
d from the easy propylation of bisrearranged calix[4]arene 7.