- Dehydrogenation of N-Heterocycles by Superoxide Ion Generated through Single-Electron Transfer
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Nitrogen-containing heteroarene motifs are found in numerous pharmaceuticals, natural products, and synthetic materials. Although several elegant methods for synthesis of these compounds through dehydrogenation of the corresponding saturated heterocycles have been reported, some of the methods are hampered by long reaction times, harsh conditions, and the need for catalysts that are not readily available. This work reports a novel method for dehydrogenation of N-heterocycles. Specifically, O2.? generated in situ acts as the oxidant for N-heterocycle substrates that are susceptible to oxidation through a hydrogen atom transfer mechanism. This method provides a general, green route to N-heteroarenes.
- Huang, Yuan-Qiong,Song, Hong-Jian,Liu, Yu-Xiu,Wang, Qing-Min
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- MODELS OF FOLATE COENZYMES-VII SYNTHESIS AND CARBON TRANSFER REACTIONS OF N5,N10-METHENYL AND N5,N10-METHYLENETETRAHYDROFOLATE MODELS
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Carboxylate esters react with 1,2-diaminoethanes to yield imidazolines, which upon consecutive reaction with acetic anhydride or tosyl chloride and methyl iodide give imidazolinium salts that serve as models of N5,N10-(CH+)-tetrahydrofolate (THF) coenzymes (7a,b and 18a,b).Reduction of the latter salts with sodium borohydride or reaction with anions (R-) give the corresponding 5,10--THF models.Mono- and bifunctional nucleophiles react with 18a,b to yield carbon-transfer products. 6-Alkylamino-1,3-dimethyluracils react with 1-tosyl-3,4,4-trimethylimidazolidine (the reduction product of 18b), in the presence of acetic acid, to form carbon-transfer products via a mechanism which bears close analogy to the mechanism of action of thymidylate synthetase.
- Bieraeugel, H.,Plemp, R.,Hiemstra, H. C.,Pandit, U. K.
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p. 3971 - 3980
(2007/10/02)
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