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ABSTRACT: Several amino acids were tested to catalyze the transition-metal-free direct C-H arylation of unactivated benzene derivatives. Among them, proline was found to be an excellent catalyst for the cross-coupling between aryl halides and unactivated arenes. The reaction presumably involves an aryl radical anion as the intermediate based on several experiments. The reaction using this catalyst system offers an option toward establishing an environmentally benign and cost-effective route to biaryls.
The Journal of Organic Chemistry 08/2012; 77(18):7844-9. · 4.45 Impact Factor
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ABSTRACT: To develop a boron carrier for practical purposes, new boron-containing amino acids with an undecahydro-closo-dodecaboranylthio ([(10)B(12)H(11)S](2-)-) unit in the side chain of the α-amino acid have already been designed and synthesized. In the present paper, cytotoxicity, the incorporation amounts into tumor cells, and the tumor cell killing effects of these compounds were elucidated to evaluate their usefulness as boron carriers. Furthermore, the microdistribution of the amino acids in tumor cells was established.
Journal of Medicinal Chemistry 07/2012; 55(15):6980-4. · 4.80 Impact Factor
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ABSTRACT: An efficient and convenient access to 1-substituted indazol-3-ones 2 has been achieved throughout the intramolecular C-N bond formations of 2-chloro-benzoic acid-N'-aryl and alkyl-hydrazides employing 0.5 mol% of cuprous (I) iodide and 20 mol% of L-proline as catalyst precursors under mild conditions in moderate to excellent yields.
Organic & Biomolecular Chemistry 12/2011; 10(7):1381-7. · 3.70 Impact Factor
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ABSTRACT: A convenient and simple synthetic method of dodecaboratethio-L-amino acid, a new class of tumor-seeking boron carrier for BNCT, was accomplished from S-cyanoethylthioundecahydro-closo-dodecaborate (S-cyanoethyl-(10)BSH, [(10)B(12)H(11)](2-)SCH(2)CH(2)CN) and bromo-L-α-amino acids by nearly one step S-alkylation. An improved synthesis of S-cyanoethyl-(10)BSH, a key starting compound for S-alkylation, was also performed by Michael addition of (10)BSH with acryronitrile in high yield. Four kinds of new dodecaboratethio-L-amino acids were obtained in optically pure form without the need for any optical resolution.
Applied radiation and isotopes: including data, instrumentation and methods for use in agriculture, industry and medicine 04/2011; 69(12):1768-70. · 1.09 Impact Factor
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ABSTRACT: D-Galacturonic acid reductase was purified from a psychrophilic yeast strain of Cryptococcus diffluens, which was isolated from Satho, a traditional alcohol drink in Thailand. This enzyme, named Cd-GalUAR, assimilates D-galacturonic acid and requires NADPH as a cofactor. Cd-GalUAR is about 45 kDa and stable from pH 6.5 to 7.5 and up to 35°C. Its optimum pH and temperature are pH 7.0 and 40°C, respectively. However, 80% of its maximum activity remained at 4°C. The reaction of Cd-GalUAR from D-galacturonic acid produces L-galactonic acid, which was identified by (13)C NMR and LC-MS. Three amino acid sequences were determined from trypsin-digested peptides of Cd-GalUAR. Similar sequences are found in many NAD or NADP oxidoreductases, including some D-galacturonate reductases. Our results suggest that Cd-GalUAR is the first D-galacturonate reductase identified in yeast.
Journal of Bioscience and Bioengineering 03/2011; 111(5):518-21. · 1.79 Impact Factor
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Advanced Synthesis & Catalysis 10/2010; 352(14‐15):2531 - 2537. · 6.05 Impact Factor
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ABSTRACT: Substituted dihydroquinozalin-2-ones (1-16) have been synthesized easily by the use of copper-catalyzed coupling method. The reactions of 2-haloanilines with a variety of alpha-amino acids in the presence of copper (I) iodide gave corresponding 3-substituted dihydroquinozalin-2-ones in up to 86% yield. Some new quinoxalin-2-ones (2, 4, 5, 13 and 16) have moderate cytotoxic activity toward HeLaS3 cell lines at 4.9-18.1microM.
Bioorganic & medicinal chemistry letters 07/2009; 19(15):4119-21. · 2.65 Impact Factor
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ABSTRACT: We found that hydroxycinnamic acid (HA) glycerol esters such as 1-sinapoyl glycerol and 1-p-coumaroyl glycerol can be synthesized through a direct esterification reaction using a type A feruloyl esterase from Aspergillus niger. The water solubilities of HA glycerol esters were higher than those of the original chemicals. HA glycerol esters absorbed ultraviolet light and scavenged 1,1-diphenyl-2-picrylhydrazyl radicals.
Bioscience Biotechnology and Biochemistry 11/2007; 71(10):2606-9. · 1.28 Impact Factor
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ABSTRACT: A simple and efficient synthesis of nicotinamide riboside (NAR) 1 and derivatives 4 and 5 via trimethylsilyl trifluoromethanesulfonate (TMSOTf)-mediated N-glycosilation followed by spontaneous deacetylation by treating with methanol is reported.
Bioorganic & Medicinal Chemistry Letters 05/2002; 12(8):1135-7. · 2.55 Impact Factor
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ABSTRACT: Both enantiomers (3 and 4) of dimethyl cis-(4-acetoxycyclopent-2-enyl)malonate (3), known intermediates for the synthesis of epijasmonate, were prepared in an enantio-enriched form from common starting material 2 based on desymmetrization of the meso-character by palladium-catalyzed asymmetric allylic alkylation.
Bioscience Biotechnology and Biochemistry 04/2002; 66(3):660-2. · 1.28 Impact Factor
