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A basic ionic liquid, 1-butyl-3-methyl imidazolium hydroxide ([bmim]OH), efficiently promotes a one-pot, three-component condensation of aromatic aldehydes, malononitrile or ethyl cyanoacetate, and 2-hydroxy-1,4-naphthoquinone to produce 4-aryl-5,10-dihydro-4 H-benzo[ g]chromene-5,10-dione derivatives in high yields at room temperature. This reaction does not involve any hazardous organic solvent and toxic catalyst. The ionic liquid is recovered and recycled for subsequent reactions. Moreover, this protocol has the advantages of easy work-up, short reaction time, high yields, and environmentally benign procedure compared with the reported methods. J. Heterocyclic Chem., (2011). [ABSTRACT FROM AUTHOR]

A mild nitration of pyrrolo[2,1‐a]isoquinolines has been reached using sodium nitrite as nitro source in HFIP at ambient temperature. A variety of nitro‐bearing pyrrolo[2,1‐a]isoquinoline derivatives has been efficiently prepared in poor to quantitative yields (28–98 %). These products can be easily transformed to primary amines and amide by simple chemical reactions. Treatment of other nitrogen‐containing heterocycles such as pyrrolo[1,2‐a]quinoline and substituted indoles under this developed reaction system afforded nitro‐bearing N‐heterocycles in relatively lower yields (15–19 %). [ABSTRACT FROM AUTHOR]

Heterocycles, a class of molecules that includes oxazoles, constitute one of the most common building blocks in current pharmaceuticals and are common in medicinally important natural products. The antitumor natural product nataxazole is a model for a large class of benzoxazole‐containing molecules that are made by a pathway that is not characterized. We report structural, biochemical, and chemical evidence that benzoxazole biosynthesis proceeds through an ester generated by an ATP‐dependent adenylating enzyme. The ester rearranges via a tetrahedral hemiorthoamide to yield an amide, which is a shunt product and not, as previously thought, an intermediate in the pathway. A second zinc‐dependent enzyme catalyzes the formation of hemiorthoamide from the ester but, by shuttling protons, the enzyme eliminates water, a reverse hydrolysis reaction, to yield the benzoxazole and avoids the amide. These insights have allowed us to harness the pathway to synthesize a series of novel halogenated benzoxazoles. [ABSTRACT FROM AUTHOR]

Heterocycles, a class of molecules that includes oxazoles, constitute one of the most common building blocks in current pharmaceuticals and are common in medicinally important natural products. The antitumor natural product nataxazole is a model for a large class of benzoxazole‐containing molecules that are made by a pathway that is not characterized. We report structural, biochemical, and chemical evidence that benzoxazole biosynthesis proceeds through an ester generated by an ATP‐dependent adenylating enzyme. The ester rearranges via a tetrahedral hemiorthoamide to yield an amide, which is a shunt product and not, as previously thought, an intermediate in the pathway. A second zinc‐dependent enzyme catalyzes the formation of hemiorthoamide from the ester but, by shuttling protons, the enzyme eliminates water, a reverse hydrolysis reaction, to yield the benzoxazole and avoids the amide. These insights have allowed us to harness the pathway to synthesize a series of novel halogenated benzoxazoles. [ABSTRACT FROM AUTHOR]

Backgrounds: Oral cancer is the 4th leading cause of cancer death for males and the top cancer in young adult males in Taiwan. Tongue squamous cell carcinoma (TSCC) is a common oral cancer and generally associated with poor prognosis. Global DNA hypomethylation at the 5 position of cytosine (5mC) is a well-known epigenetic feature of cancer. Therefore, the purpose of this study was to investigate the relationship of the global 5mC content with the tumorigenesis and prognosis of patients with TSCC.Methods: The levels of global 5mC were evaluated by immunohistochemistry using tissue microarray slides of 248 surgically resected TSCC and 202 corresponding tumor adjacent normal (TAN) tissues.Results: We found that the level of 5mC in TSCC (P < 0.001) was significantly decreased as compared to TAN. Among TSCC tissues, decreased levels of 5mC were associated with female gender (P = 0.036). In addition, the global hypomethylation was associated with the poor disease-specific survival in TSCC patients (adjusted hazard ratio: 1.55, P = 0.043), especially for patients in older age group (> 50 years, P = 0.013), with moderate or poor cell differentiation (P = 0.044), early stage of disease (I-II, P = 0.046), small tumor size (T1-T2, P = 0.005), without lymph node involvement (P = 0.041), and ever received postoperative radiotherapy (P = 0.009).Conclusions: Global hypomethylation was an independent biomarker for the development and poor prognosis of TSCC. [ABSTRACT FROM AUTHOR]