| 摘要 |
PCT No. PCT/GB96/00815 Sec. 371 Date Jul. 16, 1997 Sec. 102(e) Date Jul. 16, 1997 PCT Filed Apr. 2, 1996 PCT Pub. No. WO96/31458 PCT Pub. Date Oct. 10, 1996The subject invention concerns a process for the preparation of a compound of formula (2), which comprises phenolic oxidation of a compound of formula (1) wherein X1 and X2 are independently selected from H or a protecting group for the phenolic function, e.g. acyl or trialkylsilyl; groups A1, A2, B1, B2 and Y are selected so as to render the nitrogen atom non-basic; Z is a blocking group, e.g. Br or t-butyl; and R is H, C1-20 alkyl, C3-20 aryl, C4-20 arylalkyl, and wherein the process is carried out in a two-phase liquid system comprising an aqueous base and an organic solvent having a dielectric constant below 4.8.
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