Abstract: A process for conveniently and efficiently preparing a 2,6-dihalogenopurine using an inexpensive starting material. A process for preparing a 2,6-dihalogenopurine, comprising treating a 2-amino-6-halogenopurine having a protective group at 7th position or 9th position with a diazotizating agent and a halogen source; and a process for preparing a 9-acyl-2-amino-6-halogenopurine, comprising treating a 2-amino-6-halogenopurine with an acylating agent in the presence of a base.

Abstract: A process for conveniently and efficiently preparing a 2,6-dihalogenopurine using an inexpensive starting material. A process for preparing a 2,6-dihalogenopurine, comprising treating a 2-amino-6-halogenopurine having a protective group at 7th position or 9th position with a diazotizating agent and a halogen source; and a process for preparing a 9-acyl-2-amino-6-halogenopurine, comprising treating a 2-amino-6-halogenopurine with an acylating agent in the presence of a base.

Abstract: A process for conveniently and efficiently preparing a 2,6-halogenopurine using an inexpensive starting material. A process for preparing a 2,6-dihalogenopurine, comprising treating a 2-amino-6-halogenopurine having a protective group at 7th position or 9th position with a diazotizating agent and a halogen source; and a process for preparing a 9-acyl-2-amino-6-halogenopurine, comprising treating a 2-amino-6-halogenopurine with an acylating agent in the presence of a base.

Abstract: A process for conveniently and efficiently preparing a 2,6-halogenopurine using an inexpensive starting material. A process for preparing a 2,6-dihalogenopurine, comprising treating a 2-amino-6-halogenopurine having a protective group at 7th position or 9th position with a diazotizating agent and a halogen source; and a process for preparing a 9-acyl-2-amino-6-halogenopurine, comprising treating a 2-amino-6-halogenopurine with an acylating agent in the presence of a base.

Abstract: A 2-pyridyl-thiazolidin-4-one derivative represented by the formula: ##STR1## wherein R.sub.1 and R.sub.2 are each a hydrogen atom, an C.sub.1 -C.sub.20 alkyl group, an C.sub.2 -C.sub.20 alkenyl group, an C.sub.2 -C.sub.20 alkynyl group, an aryl group, a C.sub.3 -C.sub.8 cycloalkyl group or an aralkyl group which may have a substituent, R.sub.3 is a hydrogen atom, an C.sub.1 -C.sub.20 alkyl group, an C.sub.2 -C.sub.20 alkenyl group, an C.sub.2 -C.sub.20 alkynyl group, a C.sub.3 -C.sub.

Abstract: A cephem derivative represented by the general formula ##STR1## wherein R.sup.1 represents hydrogen or methyl, R.sup.2 represents carboxyl or esterified carboxyl, and n represents 0 or 1, or a pharmaceutically acceptable salt thereof; intermediates for the cephem derivative or salt thereof; processes for producing these compounds; and a pharmaceutical composition and method for preventing or treating bacterial infectious diseases, wherein the cephem derivative or the salt thereof is used.

Abstract: A cephem compound represent by the general formula ##STR1## wherein, R.sup.1 represents hydrogen or lower alkyl, R.sup.2 and R.sup.3 are the same or different and each represents hydrogen or lower alkyl, R.sup.4 represents carboxyl or esterified carboxyl, and n represents 0 or 1, a salt of the cephem compound, and a process for producing the cephem compound or a salt thereof. Compounds of the above formula and salts thereof are valuable as antibacterial agents and are especially useful as oral drugs in the prevention or treatment of bacterial infectious diseases.