Chemical Communications 2010-04-14

An extended cavitand with an introverted carboxylic acid.

Shengxiong Xiao, Dariush Ajami, Julius Rebek

Index: Chem. Commun. (Camb.) 46(14) , 2459-61, (2010)

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Abstract

The condensation of a Kemp's triacid derivative with a diamino resorcinarene yielded a cavitand with the deepest cavity prepared to date featuring an inwardly-directed carboxylic acid. The extended 6,7-diaminoquinoxaline wall bearing the acid allowed accommodation of large amines, such as 1-adamantanemethylamine, as well as smaller amines such as triethylamine. Adamantyl and cyclohexyl isocyanides are also bound in the deep cavitand in a way that positions the isonitrile function near the carboxylic acid group. Reaction occurs inside the cavity at ambient temperature to form the respective N-acylformamides. Low concentrations of the transient O-acyl isoamide intermediate were detected by (1)H NMR and IR spectroscopy.