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以2,5-二羟基苯乙酮(2)为原料,用水和甲苯的混合溶剂替代单一溶剂甲基异丁基酮进行选择性苄基化反应得1-[2-羟基-5-(苄氧基)苯基]乙酮(3),收率由75%提高至83%。3经硝化反应得1-[2-羟基-3-硝基-5-(苄氧基)苯基]-乙酮(4),4再采用价廉易得的二水氯化亚锡替代昂贵的二氧化铂进行硝基还原得1-[2-羟基-3-氨基-5-(苄氧基)苯基]-乙酮(5)。5经酰氯化和分子内缩合得6-苄氧基-8-乙酰基-2H-苯并[b][1,4]噁嗪-3(4H)-酮(6)。再用溴素替代四丁基三溴化铵经溴代反应得6-苄氧基-8-(2-溴乙酰基)-2H-苯并[b][1,4]噁嗪-3(4H)-酮(7),收率由74%提高至81%。7经不对称还原、分子内环合、缩合反应和去苄基保护得奥达特罗(1),纯度99.5%,总收率20.4%(以2计)。
To 2,5 - dihydroxyacetophenone (2) as raw material, a mixed solvent of water and toluene instead of a single solvent methyl isobutyl ketone selective benzylation reaction 1- [2-hydroxy-5- (benzyl Oxy) phenyl] ethanone (3), the yield increased from 75% to 83%. 3 was nitrated to give 1- [2-hydroxy-3-nitro-5- (benzyloxy) phenyl] -ethanone (4), 4 and then replaced by expensive cheap stannous chloride dihydrate Nitro-reduction with platinum dioxide to give 1- [2-hydroxy-3-amino-5- (benzyloxy) phenyl] -ethanone (5). 5 is chlorinated and condensed intramolecularly to give 6-benzyloxy-8-acetyl-2H-benzo [b] [1,4] oxazin-3 (4H) -one (6). Substitution of bromide for tetrabutylammonium tribromide followed by bromination gave 6-benzyloxy-8- (2-bromoacetyl) -2H-benzo [b] 4H) -one (7), the yield increased from 74% to 81%. 7 by the asymmetric reduction, intramolecular cyclization, condensation reaction and benzyl protection Odoterol (1), purity of 99.5%, the total yield of 20.4% (2).