Alkylation of nitroaromatics with trialkyborane

N. Palani, Karamil Jayaprakash, Shmaryahu Hoz

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7 Scopus citations


When p-dinitrobenzene is reacted with Et3B in t-BuOH or THF in the presence oft-BuOK, it yields p-nitroethylbenzene. In this report we examine the scope of this transformation by monitoring the effect of various parameters on the reaction. It has been found that the reaction is extremely sensitive to temperature and rather insensitive to the base-solvent combination used. It is also insensitive to the steric hindrance of the base: good yields were obtained using sodium 2,6-diisopropylphenoxide or when using NaH. Alkylation was obtained With a large variety of alkylboranes ranging from linear to polycyclic. Yields drop significantly if one of the nitro groups is replaced by another electron-withdrawing group. In all cases studied (CHO, PHCO, SO2Ph, and CN), it is the latter group which was preferentially displaced by the alkyl group. According to the suggested mechanism, the radical anion of the substrate combines with the alkyl radical released from the boranyl radical to form a Meisenheimer complex. The reaction takes place at the ring carbon bearing the highest spin density in accordance with ab initio calculations at the B3LYP/ 6-31+G level.

Original languageEnglish
Pages (from-to)4388-4391
Number of pages4
JournalJournal of Organic Chemistry
Issue number11
StatePublished - 30 May 2003


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