(1s, 4s, 5s) -4- bromo-6-oxabicyclo [3.2.1] octan-7-one manufacturing process of

Important as a production intermediate compounds of FXa inhibitory compound, (1S, 4S, 5S) -4- bromo-6-oxabicyclo [3.2.1] method for efficiently producing octane-7-one (1) it is an object to provide a. (S)-3-cyclohexene-1-carboxylic acid (R)-.alpha.-phenylethylamine salt, in a solvent, to process the 1,3-dibromo-5,5-dimethylhydantoin, or N- bromosuccinimide wherein, (1S, 4S, 5S) -4- bromo-6-oxabicyclo [3.2.1] the method for producing octane-7-one (1).