Lower rim modification of calix[4]arenes to incorporate a single group functionality. Single crystal X-ray structures of 5-(3-bromopropyl)-25,26,27,28-tetrahydroxycalix[4]arene and 25,27-diallyloxy-26,28-dibenzoyloxycalix[4]arene

The compound 5-(3-Bromopropyl)-25,26,27,28-tetrahydroxycalix-[4]arene has been prepared by the anti-Markownikov addition of hydrogen bromide to 5-allyl-25,26,27,28-tetrahydroxycalix[4]arene. The structure of the compound was established by a combination of 1 H, 13 C NMR and IR spectroscopy, and finally confirmed by single crystal X-ray crystallography. 5-(3-Bromopropyl)-25,26,27,28-tetra-hydroxycalix[4]arene crystallizes in a monoclinic P2 1 /n space group with a = 12.4127(9)Å, b = 20.754(4)Å, c = 19.751(3)Å, β = 97.524(8)° and Z = 8. The structure refined to R = 0.103 and R w = 0.121. A precursor compound used in the synthesis of 5-(3-bromopropyl)-25,26,27,28-tetrahydroxycalix[4]arene is the compound 5-allyl-25,26,27,28-tetrahydroxycalix[4]arene. This compound is prepared by treating 25-hydroxy-26,27,28-tribenzoyloxycalix[4]arene with sodium hydride and then allyl bromide, followed by a Claisen rearrangement and hydrolysis of the benzoyl groups. By a modification of the first step of the reaction sequence, which involves the removal of the excess sodium hydride before the addition of methanol, the compound 25,27-diallyloxy-26,28-dibenzoyloxycalix[4]arene has been prepared. The compound 25,27-diallyloxy-26,28-dibenzoyloxycalix[4]arene crystallizes in a monoclinic Pn space group with a = 10.840(2) Å, b = 13.958(2) Å, c = 12.928(2) Å, β = 98.23(1)° and Z = 2. The structure refined to R = 0.071 and R w = 0.091.