General Papers ARKIVOC 2006 (i) 128-133
Simple reduction of ethyl, isopropyl and benzyl aromatic esters to alcohols using sodium borohydride-methanol system
Jorge C. S. da Costa, Karla C. Pais, Elisa L. Fernandes, Pedro S. M. de Oliveira, Jorge S. Mendonça, Marcus V. N. de Souza*, Mônica A. Peralta, and Thatyana R.A. Vasconcelos
FIOCRUZ- Fundação Oswaldo Cruz, Instituto de Tecnologia em Fármacos- Far Manguinhos.Rua Sizenando Nabuco, 100, Manguinhos, 21041-250 Rio de Janeiro-RJ Brazil E-mail:
[email protected]
Abstract
Several aromatic ethyl, isopropyl and benzyl esters were reduced to their corresponding alcohols in sodium borohydride-methanol system. The reductions were completed within 15-60 minutes in refluxing THF. The alcohol products were isolated after aqueous workup in good to excellent yields (63-100%). The general procedure presented is simple, safe, inexpensive and with good perspective in industrial scale.
Keywords: NaBH4, aromatic esters, reduction
Introduction
Reduction plays a very important role in organic synthesis. One of the most common reagent used for this purpose is sodium borohydride.1 Usually, the reactions carried out with NaBH4 are safe, inexpensive and can be done in mild conditions.2,3
Although this reducing agent has been constantly used for reduction of aldehydes, ketones and other important functional groups, it is not common to use NaBH4 itself for reduction of esters.4-6
Due to this low reactivity towards esters, additives which enhance the activity of NaBH4 have been reported.7 For example, addition of iodine to NaBH4 in THF provides H3B–THF, which is useful for hydroborations, reduction of esters and various others functional groups.8 Another example is the addition of zinc chloride in presence of tertiary amine that exhibits a reducing property toward ester function.7 In this context, the aim of the present article is to describe a simple one-pot different aromatic ethyl, isopropyl and benzyl esters reduction into the corresponding alcohol using NaBH4-MeOH
ISSN 1424-6376 Page 128 ©ARKAT
