Tomomi Ikemoto

Imide-catalyzed oxidation system: sulfides to sulfoxides and sulfones.

A new combination system, the oxidation of sulfides using aqueous NaOCl in the presence of a catalytic amount of imide under two-phase conditions, has been developed. The combination effectively converts various sulfides to the corresponding sulfoxides and sulfones. It was deduced that the imide could react with NaOCl to produce N-chloroimide, which would play roles of both the active oxidizing reagent and phase transfer catalyst.

Practical synthesis of (R)-(+)-6-(1,4-dimethoxy-3-methyl-2-naphthyl)-6-(4-hydroxyphenyl)hexanoic acid: a key intermediate for a therapeutic drug for neurodegenerative diseases

Abstract A practical method for the preparation of ( R )-(+)-6-(1,4-dimethoxy-3-methyl-2-naphthyl)-6-(4-hydroxyphenyl)hexanoic acid ( R )- 2 , a key intermediate for a therapeutic drug for neurodegenerative diseases, has been developed. rac -Methyl 6-(1,4-dimethoxy-3-methyl-2-naphthyl)-6-(4-(propionyloxy)phenyl) hexanoate rac - 9b was synthesized from 2-methylnaphthoquinone in seven steps. An optically active ester ( R )- 9b was readily obtained from the corresponding racemic ester by lipase-catalyzed resolution, followed by sulfation or phosphorylation. Sulfation by a sulfur trioxide pyridine complex or phosphorylation by phosphoryl chloride enabled facile isolation of the optically active ester simply by extraction. Optically active acid ( R )- 2 was synthesized in excellent enantiomeric excess by hydrolysis of ( R )- 9b followed by recrystallization. The present synthesis of ( R )- 2 was accomplished in 10 steps without requiring chromatographic purification.

Large-scale synthesis of new cyclazines, 5-thia-1,8b-diazaacenaphthylene-3-carboxylic acid derivatives having the peripheral 12π-electron ring system

Abstract The 5-thia-1,8b-diazaacenaphthylenes ( 2 and its ester, 8 ) are new cyclazines, in which a paramagnetic ring is present in the peripheral 12π-electron ring system. Three convenient methods of preparing 8 have been developed. One involved thioglycolation of a new compound, 5-fluoroimidazo[1,2- a ]pyridine ( 6b ), followed by the Duff reaction gave 8 in 64% yield without chromatographic purification.

A Practical Synthesis of the Chronic Renal Disease Agent, 4,5-Dihydro-3H-1,4,8b-triazaacenaphthylen-3-one Derivatives, Using Regioselective Chlorination of Ethyl 5-methylimidazo[1,2-a]pyridine-3-carboxylate with N-Chlorosuccinimide

Abstract A convenient synthesis of the chronic renal disease agent, trifluoro-N-[4-(3-oxo-3,5-dihydro-4H-1,4,8b-triazaacenaphthylen-4-yl)butyl]methanesulfonamide (1a), for large scale has been developed via ethyl 5-(chloromethyl)imidazo[1,2-a]pyridine-3-carboxylate (3), which was given by the regioselective chlorination of ethyl 5-methylimidazo[1,2-a]pyridine-3-carboxylate (6) with N-chlorosuccinimide (NCS) using AcOEt as a solvent in 83% yield. The condensation of 3 and primary amines gave 4,5-dihydro-3H-1,4,8b-triazaacenaphthylen-3-one derivatives (1) in good yields. The present synthesis of 1a was accomplished in five steps from 2-amino-6-methylpyridine (4) without requiring a chromatographic method.

Convenient efficient synthesis of TAK-779, a nonpeptide CCR5 antagonist: development of preparation of various ammonium salts using trialkylphosphite and N-halogenosuccinimide

Abstract A convenient and efficient synthesis of TAK-779 (1a), a nonpeptide CCR5 antagonist, has been achieved. The new methylation of tertiary amine (2) using trimethyl phosphite and N-chlorosuccinimide, followed by the addition of HCl led to ammonium chloride (1a) in 89% isolated yield without requiring a chromatographic method. By this preparation, ammonium methanesulfonate (1e) could be obtained in 75% isolated yield.

Efficient syntheses of a novel 5-thia-1-azacycl[3.3.2]azine ring system and 3H-1,4-diazacycl[3.3.2]azine derivatives

Novel 5-thia-1-azacycl[3.3.2]azine derivatives 1 , 5-thia-1,8b-diazaacenaphthylenes, have successfully been prepared. An X-ray crystallographic analysis of 1c revealed that the 5-thia-1-azacycl[3.3.2]azine ring system adopts a planar structure as to the internal ring nitrogen atom. The 1 H NMR spectrum for unsubstituted ring system 1d implies contribution of a paramagnetic ring current in the peripheral 12π-electron ring system. Also, 3 H -1,4-diazacycl[3.3.2]azine derivatives, 4-benzyl-4,5-dihydro-3 H -1,4,8b-triazaacenaphthylen(e)-3-ones 2 and -3,5-diones 3 were synthesized with high efficiency via 3-(trichloroacetyl)imidazo[1,2- a ]pyridine derivatives as new useful synthetic intermediates.

Design and synthesis of a novel 2-oxindole scaffold as a highly potent and brain-penetrant phosphodiesterase 10A inhibitor

Highly potent and brain-penetrant phosphodiesterase 10A (PDE10A) inhibitors based on the 2-oxindole scaffold were designed and synthesized. (2-Oxo-1,3-oxazolidin-3-yl)phenyl derivative 1 showed the high P-glycoprotein (P-gp) efflux (efflux ratio (ER)=6.2) despite the potent PDE10A inhibitory activity (IC50=0.94 nM). We performed an optimization study to improve both the P-gp efflux ratio and PDE10A inhibitory activity by utilizing structure-based drug design (SBDD) techniques based on the X-ray crystal structure with PDE10A. Finally, 1-(cyclopropylmethyl)-4-fluoro-5-[5-methoxy-4-oxo-3-(1-phenyl-1H-pyrazol-5-yl)pyridazin-1(4H)-yl]-3,3-dimethyl-1,3-dihydro-2H-indol-2-one (19e) was identified with improved P-gp efflux (ER=1.4) and an excellent PDE10A inhibitory activity (IC50=0.080 nM). Compound 19e also exhibited satisfactory brain penetration, and suppressed PCP-induced hyperlocomotion with a minimum effective dose of 0.3mg/kg by oral administration in mice.