Studies on the reduction of natural aminoacids, amides such as pyrrolidines, compounds containing nitro group using tetrabutylammonium fluoride and polymethylhydrosiloxane

Abstract

The development of methods and mechanisms for safe and clean reduction is still a vast area for scientific researches. In 1997 N. J. Lawrence; L. Sekhri and co-workers reported the convenient procedure for the reduction of esters, Carboxylic acids, ketones, and aldehydes using tetrabutyl- ammonium fluoride (TBAF) and polymethylhydrosiloxane (PMHS) to the corresponding alcohols. We now found that the same transformation as a mild, environmentally friendly method for reduction of can be achieved with a range of α-aminoacids (1a-1h) which have been converted efficiently to the corresponding β-aminoalcohols: 2-amino-3-methylpentan-1-ol [isoleucinol (2a)], 2-amino-4-(methylthio)butan-1-ol [methioninol (2b)], 2-amino-3-methylbutan-1-ol [valinol (2c)], 2-amino-3-(4’-hydroxyphenyl) propan-1-ol [tyrosinol (2d)], 2-amino-3-phenylethan-1-ol [phenylglycinol (2e)], 2-amino-3-phenylpropan-1-ol [phenylalaninol (2f)], 2-aminoethan-1-ol [glycinol (2g)], and 2-aminopropanol-1-ol [alaninol (2h)], with polymethylhydrosiloxane, PMHS, in the presence of catalytic tetrabutylammonium fluoride, TBAF with > 61% yield. Carboxylic acid derivatives such as amides (3a and 3b) have also been reduced to the corresponding amines: N-ethylaniline (4a) and N-methylaniline (4b) with polymethylhydrosiloxane, PMHS, in the presence of catalytic tetrabutylammonium fluoride, TBAF with > 74% yield. We also found that this transformation can be achieved for the reduction of aromatic nitro compounds to the corresponding amines. A range of aromatic nitro compounds such as (m-Nitroaniline 5a and p-Nitroaniline 6a) have been converted efficiently to the corresponding aromatic amines: 1, 3-diaminobenzene (5b), and 1,4-diaminobenzene (6b) with > 61% yield. The resulting products were identified by comparison their spectra with those of authentic samples.