Synthesis of novel proton-ionizable calix[4]arenes

Date

2006-05

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Abstract

A series of p-tert-butylcalix[4]arenes was synthesized with enlongated acidic groups, 4-oxybutanoic acid, 5-oxypentanoic acid, N-(X)sulfonyl 4-oxybutanamide and N-(X)sulfonyl 5-oxypentanamide, on the lower rim as proton ionizable groups with or without tert-butyl groups on the upper rim. Calix[4]arenes with butoxy groups instead of methoxy groups, which are fixed in the cone conformation, are also prepared.

An efficient synthesis route for p-benzoyl and p-benzyl-substituted calix[4]arenes is reported. Further preparation of novel proton-ionizable calix[4]arenes with four benzoyl or benzyl groups on the upper rim and two methoxy groups and two N-(X)sulfonyl carboxamide groups on the lower rim are described.

Di-p-benzoyl- and di-p-benzyl substituted calix[4]arenes were synthesized to achieve individual control of the para substituent of the four aromatic rings and further preparation of proton-ionizable calix[4]arenes with two methoxy groups and two N-(X)sulfonyl carboxamide groups on the lower rim was achieved.

The syntheses of di-p-nitrocalix[4]arenes was accomplished by ipso-substitution. Proton-ionizable calix[4]arenes with two tert-butyl groups and two nitro groups on the upper rim and either one methoxy group and two N-(X)sulfonyl carboxamide groups or two methoxy groups and one N-(X)sulfonyl carboxamide group on the lower rim were synthesized.

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Keywords

Proton ionizable groups, Calix[4]arenes, Synthesis

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