To obtain the subject new compounds useful for preventing, inhibiting or treating diseases caused by the uncontrolled release of a protease, especially emphysema or cystic fibrosis, as inhibitors against a protease, especially against human leucocytic esterase.

A compound of formula I {R1 and R2 are each H or Br; R3 is Br or OH; R4 is methyl; R5 is a group of the formula: OR6 [R6 is H, an alkyl (aryl)] or the like; (n) is 0-2} or a compound of formula II {R3 is methyl; R4 is H or a group of the formula: COOR5 [R5 is H or an alkyl (aryl)] or the like}. For example, 3-bromo-7,7-dibromo-3-methylcepham-4-carboxylic acid benzyl ester. The compound of formula I or formula II is obtained by thermally reacting a compound of formula III {R3 is a group of the formula: OR4 [R4 is H, an alkyl(aryl)] or the like; (n) is 1} in a solvent, if necessary, in the presence of tetrabutylammonium bromide, isolating the product and, if necessary, subsequently oxidizing the product.