Fries重排合成3-乙酰基-2-羟基苯甲醛肟

Synthesis of 3-Acetyl-2-hydroxybenzaldehyde Oxime by Fries Rearrangement

邻羟基苯乙酮衍生物是合成查尔酮、黄酮、萘醌、农药等生物活性化合物的重要中间体,采用传统的Lewis酸催化缺乏竞争力并存在环境压力,选用PPA做Fries重排反应的催化剂及溶剂,设计了(1)水杨醛经酯化、肟化、Fries重排和(2)水杨醛经肟化、酯化、Fries重排两条反应路线,实验结果表明,路线(2)较好,水杨醛在氧化锌催化下与羟胺反应生成水杨醛肟,再经乙酸酐与酚羟基和肟羟基反应同时引入乙酰基,两步产率均超过90.0%。再以80%PPA为催化剂,在150℃条件下反应2 h,完成酚酯的选择性Fries重排合成新化合物3-乙酰基-2-羟基苯甲醛肟(AHbdO),产率22.4%,HPLC纯度99.33%。化合物分子结构经;HNMR、;CNMR、TLC-MS确证,研究为此类化合物反应提供了一种新的高效绿色合成方法。

O-Hydroxyacetophenone derivatives are important intermediates for the synthesis of bioactive compounds such as chalcone,flavonoids,naphthoquinones,pesticides,etc.Lack of competitiveness and environmental pressures with traditional Lewis acid catalysis.PPA was used as the catalyst and solvent for the Fries rearrangement reaction,and two reaction routes were designed:(1)Salicylaldehyde via esterification,oximation,Fries rearrangement and(2)Salicylaldehyde via oximation,esterification,and Fries rearrangement.The results showed that route(2)was preferable.Salicylaldehyde reacted with hydroxylamine under the catalysis of zinc oxide to form salicylaldoxime,which was then reacted with phenol hydroxyl and oxime hydroxyl by acetic anhydride to simultaneously introduce acetyl group.The yields of the two steps were more than 90.0%.Then 80%PPA was used as the catalyst to react at 150℃for 2 h to complete the selective Fries rearrangement of phenol ester to synthesize the new compound 3-acetyl-2-hydroxybenzaldehyde oxime(AHbdO)with the yield of 22.4%and the purity of 99.33%by HPLC.The structure was confirmed by;HNMR,;CNMR and TLC-MS.This work provides a new efficient and green synthesis method for the reaction of these compounds.