由异构氨基酸合成异构羟基酸

uced pressure to obtain crude semi-solid product(820 g). The crude product was purified by stirring in a mixture of diisopropylether Wild ethyl acetate. It was filtered and washed with diisopropyl ether.The dark yellowish product obtained was dried in an oven at 55 .deg.C-60.deg.C. The product weighs about 235 g (47 percent yield). The HPLC assay was98.4 percent and enatiomeric excess was 98 percent

【 Patent; CADILA HEALTHCARE LIMITED; Publ.: WO2005/19152 A2 (2005/03/03),Appl.: WO2004-IN156 (2004/06/04)】

A solution of sodium nitrite (51.8 g, 720 mmol) in 200 ML of water was added dropwise over 6 hours to a stirred solution of L-phenylalanine (33.04 g,200 mmol) in 500 ML of 10percent sulfuric acid at 50.deg. C. After the additionwas complete, the reaction mixture was stirred for 3 hours at 50.deg. C, thenat room temperature overnight.. The reaction mixture was extracted with ethylacetate (3*200 ML, 2*100 ML), then the combined organic extract was washed withwater and brine, dried over sodium sulfate and evaporated to yield 28.98 g of ayellow solid. Recrystallization from benzene afforded 22.15 g of the title Acompound as white needles, m.p. 120.deg.-124.deg. C.

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