Sadakazu Yokomori

Structure–Activity Characterization of an H2-Receptor Antagonist, 3-Amino-4-[4-[4-(1-piperidinomethyl)-2-pyridyloxy]-cis-2-butenylamino]-3-cyclobutene-1,2-dione Hydrochloride (IT-066), Involved in the Insurmountable Antagonism against Histamine-Induced Positive Chronotropic Action in Guinea Pig Atria

IT-066 (3-amino-4-[4-[4-(1-piperidinomethyl)-2-pyridyloxy]-cis-2- butenylamino]-3-cyclobutene-1,2-dione hydrochloride), an H2-receptor antagonist, shows highly potent, time-dependent, and irreversible antagonism at H2-receptors. We identified the structurally important parts of IT-066 involved in its interaction with the H2-receptor, and explored its unique mode of action by investigating the H2-receptor blocking action of IT-066 and related compounds in guinea pig isolated atria. IT-066 is structurally divided into three different parts: a tertiary amine and hydrophobic group, a connecting carbon chain, and a polar group. Though the replacement of its pyridine ring with a benzene ring maintained the mode of the H2-receptor blocking action of IT-066, the oxidation of the piperidine ring completely attenuated this blocking action. By replacing the connecting carbon chain of IT-066, cis-2-butene, with butane, trans-2-butene, or 2-butyne, the irreversible antagonism disappeared and the potency was reduced. On the other hand, BMY25368, whose connecting carbon chain is trimethylene, showed irreversible antagonism comparable to that of IT-066. Hydrolysis of the polar group of IT-066 completely attenuated the H2-receptor blocking activity. Among the compounds tested, only the compound that had 3,4-diamino-3-cyclobutene-1,2-dione as a polar group showed time-dependent and insurmountable H2-receptor blocking action. These data suggest the importance of the following structural features of IT-066: the piperidine ring of IT-066 and -NH2 in its polar group are essential for the interaction with the H2-receptor; and the 3,4-diamino-3-cyclobutene-1,2-dione group and the connecting carbon chain of IT-066 are crucial for determining the irreversibility of H2-receptor blocking action, though the connecting carbon chain is replaceable with another chain with appropriate length and configuration.

Synthesis and antirheumatic activity of the metabolites of esonarimod.

We have developed esonarimod, (+/-)-2-acetylthiomethyl-4-(4-methylphenyl)-4-oxobutanoic acid, as a new antirheumatic drug. Now we describe herein the preparation of the enantiomers of (+/-)-deacetylesonarimod, the pharmaceutically active metabolites of esonarimod, and comparison of their antirheumatic activities. No significant difference has been observed between the two enantiomers. In a pre-clinical study of esonarimod, other metabolites were detected in rat blood or urine. We also synthesized these compounds as authentic samples to analyze the human metabolites in clinical studies of esonarimod.

Synthesis of dihydrothiophene derivatives as metabolites of esonarimod

Three compounds with a dihydrothiophene ring were synthesized as authentic samples to analyze human metabolites of Esonarimod, which has been developed as a new antirheumatic drug.

A Practical Procedure for the Synthesis of Esonarimod, (R,S)-2-Acetylthiomethyl-4- (4-methylphenyl)-4-oxobutanoic Acid, an Antirheumatic Agent. II

Abstract An efficient large-scale synthesis of Esonarimod, (R,S)-2-acetylthiomethyl-4-(4-methylphenyl)-4-oxobutanoic acid (1), a new antirheumatic drug, was established. A small amount of water increased the yield of the Michael addition of thioacetic acid (4) to 2-methylene-4-(4-methylphenyl)-4-oxobutanoic acid (2) to give 1. Multikilogram amounts of 1 (over 25 kg) were successfully obtained using this procedure. In addition, this procedure was repeated nine times, and reproducible results were obtained. See Ref. [1]