Improvements in or relating to the preparation of 1-(ú­-nitro-phenyl)-2-acylamido-propane-1,3-diols

摘要

1 - (p - Nitrophenyl) - 2 - acylamidopropane-1 : 3-diols are prepared by reducing a b -phenylserine derivative of the general formula: FORM:0796901/IV (b)/1 (wherein R1 is hydrogen or a hydrocarbon residue) with a metal borohydride, treating the resulting metal complex compound of b -(p-nitrophenyl)-serinol with a mild acylating agent and decomposing the resulting acylated metal complex compound (e.g. with aqueous mineral acid or aqueous alkali). Suitable borohydrides are those of lithium, sodium and especially the alkaline-earth metals, whilst acylation may be effected with acid halides or especially with esters of halogenated acids. In examples: (1) D - (-) - threo - b - (p - nitrophenyl) - serine methyl ester is stirred with an ethanolic solution of calcium borohydride (prepared in situ from sodium borohydride and calcium chloride), and the product is refluxed with methyl dichloroacetate and decomposed with dilute hydrochloric acid to form chloramphenicol; (2) the reducing agent in (1) is replaced by a calcium borohydride-tetrahydrofuran complex. Additional starting materials are listed, and reference is made to acetyl and benzoyl as acyl substituents.