Treatment of calixarene bis-O-carbamates 4a,b-6a,b with LDA in THF results in the regio- and stereoselective introduction of both axial and equatorial carboxamide groups at the methylene bridges via a homologous anionic ortho-Fries rearrangement to give 7-16. The stereochemical outcome of the rearrangement is dependent on the reaction conditions and the conformation of the starting material. Stereochemical and structural proof has been secured by the X-ray crystal structure of calixarene 10 having only one equatorial carboxamide moiety. The use of this novel class of methylene bridge-functionalized calixarenes is illustrated by the formation of bis--lactone 19, while the enhanced acidity of the remaining hydroxyl groups, owing to the presence of axial carboxamide groups at the methine bridges, followed from the easy propylation of bisrearranged calixarene 7.
Middel, O., Greff, Z., Taylor, N. J., Verboom, W., Reinhoudt, D., & Snieckus, V. (2000). The first lateral functionalization of calixarenes by a homologous anionic ortho-Fries rearrangement. Journal of organic chemistry, 65(3), 667-675. https://doi.org/10.1021/jo990976y