Chlorofullerene C60Cl6: a precursor for straightforward preparation of highly water-soluble polycarboxylic fullerene derivatives active against HIV.

We report for the first time the application of chlorofullerene C60Cl6 as a substrate for straightforward preparation of highly water-soluble fullerene derivatives, promising compounds for investigation of the biological action of fullerenes in vitro and in vivo. Methyl esters of phenylacetic and benzylmalonic acids were used as reagents in the Friedel-Crafts arylation of C60Cl6 that resulted in the corresponding C60(Ar)5Cl compounds with 50-60% yields. The following cleavage of ester groups in phenylacetic and benzylmalonic residues was accomplished almost quantitatively to yield the corresponding fullerene-based acids bearing 5 and 10 carboxylic groups, respectively.

Photoaddition of N-substituted piperazines to C60: an efficient approach to the synthesis of water-soluble fullerene derivatives.

An oxidative radical photoaddition of mono N-substituted piperazines to [60]fullerene was systematically investigated. Reactions of C60 with piperazines bearing bulky electron-withdrawing groups (2-pyridyl, 2-pyrimidinyl) were found to be the most selective and yielded C60(amine)4O as major products along with small amounts of C60(amine)2. In contrast, interactions of fullerene with N-methylpiperazine and N-(tert-butoxycarbonyl)piperazine were found to have low selectivity due to different side reactions.

Unexpected interconversion reaction of 1,4-diaminofullerenes.

A facile substitution of amine groups attached to the fullerene cage occurs when 1,4-diaminofullerenes C60[NR2]2 are allowed to react with excess of another amine R'2NH; this reaction proceeds rapidly at room temperature without any additional initiators.