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STUDIES ON KETENE AND ITS DERIVATIVES. CI. REACTION OF DIKETENE WITH 4-AMINO-METHYLPYRIDINE 1-OXIDES
Kato, Tetsuzo,Katagiri, Nobuya,Tanaka, Michiko (nee Ishikawa),Wagai, Akihiro,Harimaya, Kenzo
, p. 2129 - 2135 (2007/10/02)
The reaction of diketene with 4-amino-methylpyridine 1-oxides was examined. 4-aminopyridine 1-oxide (1a) and 4-amino-3-methylpyridine 1-oxide (1c) reacted with diketene in the presence of triethylamine 0--5 deg C to give the corresponding substituted 2,6-dimethyl-4-pyrone-3-carboxamides; i.e., N-(1-oxido-4-pyridyl) (3a) and N-(3-methyl-1-oxido-4-pyridyl) (3c) compounds.The reaction of diketene with 4-amino-methylpyridine 1-oxides (1b, d, and e) afforded 4-acetoamidopyridine 1-oxides (2b, d, and e) under the same conditions.However, the reaction of diketene with 4-aminopyridine 1-oxides (1f and g) possessing an ethyl group at the 3-position gave N-(3-ethyl-1-oxido-4-pyridyl)-2-acetyl-3,5-dimethylphenol-4-carboxamides (5f and g), together with N-(3-ethyl-1-oxido-4-pyridyl)-2,6-dimethyl-4-pyrone-3-carboxamides (3f and g).The mechanism of formation of compounds 5f and g is discussed.Keywords--diketene; amino-methylpyridine 1-oxides; triethylamine; aceto-acetamidopyridines; N-pyridyl-2,6-dimethyl-4-pyrone-3-carboxamides; N-pyridyl-2-acetyl-3,5-dimethylphenol-4-carboxamides; catalytic reduction; hydrolysis
