Calix arene esters rearrangement

As an alternative to electrophilic substitution as a means for introducing functional groups into the calixarenes, a reaction sequence has been developed that involves the conversion of calix[4]arene (59) to the tetraallyl ether 63. When 63 is heated in diethylaniline it undergoes a four-fold p-Claisen rearrangement to afford p-allyl-calix[4]arene (62) in excellent yield 126). From the tetra-tosyl ester of 62 (i.e. compound 66 a) a variety of functionalized calixarenes have been obtained, including the aldehyde 66b, alcohol <56 c, bromide 66 d, azide 66 e, amine 66f, and nitrile 66g. Removal of the tosyl group occurs under mildly basic conditions to yield, for example, p-(2-hydroxyethyl)calix[4]arene (66 h). 

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