Studies on Uricosuric Diuretics. V. Convenient and Efficient Synthesis of 2,3-Dihydrobenzofuran Derivatives.
作者:Haruhiko SATO、Kiyonori KUROMARU、Takenori ISHIZAWA、Bunya AOKI、Hiroshi KOGA
DOI:10.1248/cpb.40.2597
日期:——
A practical procedure for synthesis of a new uricosuric agent, 5-chloro-7, 8-dihydro-3-phenylfuro[2, 3-g]-1, 2-benzisoxazole-7-carboxylic acid (1, AA-193) is described, which starts from 2, 5-dichlorophenol (3b) and involves 5-chloro-6-hydroxy-3-phenyl-1, 2-benzisoxazole (2) as the key intermediate. Successive treatment of 3b with benzoyl chloride-aluminum chloride (AlCl3) and hot ethanolic sodium hydroxide gives 4-benzoyl-2, 5-dichlorophenol (8, 61%), which is oximated with hydroxylamine hydrochloride and then transformed into the benzisoxazole 2 (88%) with potassium hydroxide in N, N-dimethylformamide (DMF) (method C). The reaction of 2 with aqueous formaldehyde and dimethylamine affords the Mannich base 11a (97%), which is treated with a sulfonium ylide 12, 14 or 15 followed by heating with sodium hydroxide (NaOH) in ethanol (EtOH) to give 1 in high yield (method E).
一种合成新型尿酸排泄剂5-氯-7, 8-二氢-3-苯基呋喃[2, 3-g]-1, 2-苯异噁唑-7-羧酸(1,AA-193)的实用程序被描述,该程序以2, 5-二氯酚(3b)为起始物,并以5-氯-6-羟基-3-苯基-1, 2-苯异噁唑(2)作为关键中间体。3b依次与苯甲酰氯-氯化铝(AlCl3)和热乙醇钠氢氧化物反应,得到4-苯甲酰-2, 5-二氯酚(8,61%),该化合物与氢氧化铵反应后,再用氢氧化钾在N, N-二甲基甲酰胺(DMF)中转化为苯异噁唑2(88%)(C法)。化合物2与水溶性甲醛和二甲胺反应生成Mannich碱11a(97%),然后与亚磺基阳离子12、14或15反应,随后在乙醇(EtOH)中与氢氧化钠(NaOH)加热反应,最终高产率获得化合物1(E法)。