反应详情

5-methoxy-1-oxo-1,2,3,4-tetrahydro-naphthalene-2-carboxylic acid ethyl ester (2,34 g; 8a) (Genet, J. P., et al., Tetrahedron Lett. 35 (1994) 4559-4562) is treated with ethyl-6-bromo-hexanoate in a analogues way to that described for the conversion of 3a in example 3. This resulted in a mixture of 6-(5-methoxy-1-oxo-1,2,3,4-tetrahydro-naphthalen-2-yl)-hexanoic acid (8b) and 2-(5-Carboxy-pentyl)-5-methoxy-1-oxo-1,2,3,4-tetrahydro-naphtalene-2-carboxylic acid ethyl ester (8c) in a ratio of approximately 1:1. This mixture of acids is treated with O-benzylhydroxylamine in a similar way as described for the conversion of 2b into 2c in example 2. The crude product is subjected to column chromatography yielding an inseparable mixture of 2-(5-benzyloxycarbamoyl-pentyl)-5-methoxy-1-oxo-1,2,3,4-tetrahydro-naphtalene-2-carboxyclic acid ethyl ester (8d) and 6-(5-methoxy-1-oxo-1,2,3,4-tetrahydro-naphtalen-2-yl)-hexanoic acid benzyloxy-amide (8e). This mixture is hydrogenated in methanol with Pd/C/BaSO4 as a catalyst.

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