Treatment of isoquinolinecarboxamide 4a with triethyl orthoformate, chloroacetyl chloride or carbon disulfide afforded the pyrimidinone 7, oxopyrimidinethione 12 and chloromethylpyrimidinone 18, respectively. These products were used as versatile starting materials for synthesis of other heterocyclic compounds. The heterocyclic hydrazide 6 was also obtained.

Treatment of isoquinolinecarboxamide 4a with triethyl orthoformate, chloroacetyl chloride or carbon disulfide afforded the pyrimidinone 7, oxopyrimidinethione 12 and chloromethylpyrimidinone 18, respectively. These products were used as versatile starting materials for synthesis of other heterocyclic compounds. The heterocyclic hydrazide 6 was also obtained.

4-Oxo-1-phenyl-4,7-dihydropyrazolo[3,4-b]pyridine-5-carbonitrile compound (4) was prepared by the reaction of 5-amino-3-methyl-1-phenyl pyrazole (1) with ethyl 2-cyano-3-ethoxyacrylate followed by cyclization using diphenyl ether. The pyrazolopyridinone compound 4 was converted to the chloropyrazolopyridine 5 by the reaction with phosphorus oxychloride. Compound 5 was used as a starting material to synthesize 3-amino-4-substituted pyrazolothienopyridine derivatives 10a–f and ethyl-3- aminopyrazolopyrrolopyridine-2-carboxylate 21, which were used as a versatile precursors for synthesis of poly-fused heterocyclic compounds.

4-Oxo-1-phenyl-4,7-dihydropyrazolo[3,4-b]pyridine-5-carbonitrile compound (4) was prepared by the reaction of 5-amino-3-methyl-1-phenyl pyrazole (1) with ethyl 2-cyano-3-ethoxyacrylate followed by cyclization using diphenyl ether. The pyrazolopyridinone compound 4 was converted to the chloropyrazolopyridine 5 by the reaction with phosphorus oxychloride. Compound 5 was used as a starting material to synthesize 3-amino-4-substituted pyrazolothienopyridine derivatives 10a–f and ethyl-3- aminopyrazolopyrrolopyridine-2-carboxylate 21, which were used as a versatile precursors for synthesis of poly-fused heterocyclic compounds.

4-Oxo-1-phenyl-4,7-dihydropyrazolo[3,4-b]pyridine-5-carbonitrile compound (4) was prepared by the reaction of 5-amino-3-methyl-1-phenyl pyrazole (1) with ethyl 2-cyano-3-ethoxyacrylate followed by cyclization using diphenyl ether. The pyrazolopyridinone compound 4 was converted to the chloropyrazolopyridine 5 by the reaction with phosphorus oxychloride. Compound 5 was used as a starting material to synthesize 3-amino-4-substituted pyrazolothienopyridine derivatives 10a–f and ethyl-3- aminopyrazolopyrrolopyridine-2-carboxylate 21, which were used as a versatile precursors for synthesis of poly-fused heterocyclic compounds.

4-Oxo-1-phenyl-4,7-dihydropyrazolo[3,4-b]pyridine-5-carbonitrile compound (4) was prepared by the reaction of 5-amino-3-methyl-1-phenyl pyrazole (1) with ethyl 2-cyano-3-ethoxyacrylate followed by cyclization using diphenyl ether. The pyrazolopyridinone compound 4 was converted to the chloropyrazolopyridine 5 by the reaction with phosphorus oxychloride. Compound 5 was used as a starting material to synthesize 3-amino-4-substituted pyrazolothienopyridine derivatives 10a–f and ethyl-3- aminopyrazolopyrrolopyridine-2-carboxylate 21, which were used as a versatile precursors for synthesis of poly-fused heterocyclic compounds.

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We report the effects of Mn substitution, corresponding to hole doping, on the electronic properties of the narrow gap semiconductor, FeSb2, using single crystals of Fe1‒xMnxSb2 grown by the Sb flux method. The orthorhombic Pnnm structure was confirmed by powder X-ray diffraction (XRD) for the pure and Mn-substituted samples. Their crystal structure parameters were refined using the Rietveld method. The chemical composition was investigated by wavelength-dispersive X-ray spectroscopy (WDX). The solubility limit of Mn in FeSb2 is xmax ~ 0.05 and the lattice constants change monotonically with increasing the actual Mn concentration. A drastic change from semiconducting to metallic electronic transports was found at very low Mn concentration at x ~ 0.01. Our experimental results and analysis indicate that the substitution of a small amount of Mn changes drastically the electronic state in FeSb2 as well as the Co-substitution does: closing of the narrow gap and emergence of the density of states (DOS) at the Fermi level.

Single crystals of the shandite-type half metallic ferromagnet Co3Sn2S2, and its In-substituted compounds, Co3Sn2−xInxS2 (0