The chemistry of 5-oxodihydroisoxazoles. Part 22.1 The synthesis of 1,3-oxazin-6-ones from N-thioacylisoxazol-5(2H )-ones
作者:David S. Millan、Rolf H. Prager
DOI:10.1039/a804527e
日期:——
N-Thioacylisoxazol-5(2H)-ones, prepared by the reaction of thiocarbonyl chlorides with isoxazol-5(2H)-ones in the presence of base, are reduced by triphenylphosphine to afford 1,3-oxazin-6-ones and triphenylphosphine sulfide. If the thioacylation is carried out with phenyl chlorodithioformate, the thermal rearrangement of the intermediate, to again form the oxazin-6-one and sulfur, is so rapid that the use of the phosphine is not required. The presence of an ethoxycarbonyl group at C-3, or of a bromine atom at C-4 of the isoxazolone results in the formation of thiazoles.
Synthesis of 5-bromo-2,4-dimethyloxazole by flash-vacuum pyrolysis of 2-acetyl-4-bromo-3-methylisoxazol-5(2H)-one
作者:J. Khalafy、A. Poursattar Marjani、A. R. Molla Ebrahimlo
DOI:10.1007/s10593-008-0002-z
日期:2008.1
Chemistry of 5-oxodihydroisoxazoles. Part 17.1 Acylation of 5-oxodihydroisoxazoles
作者:Rolf H. Prager、Jason A. Smith、Ben Weber、Craig M. Williams
DOI:10.1039/a700133i
日期:——
2-Unsubstituted isoxazol-5(4H)-ones and
-5(2H)-ones may be acylated by acid chlorides,
anhydrides or carboxylic acids in the presence of carbodiimides, to give
O- and N-acylated products. The solvent, the presence
of base and the temperature are found to alter the product ratios
dramatically, but the substituents present at C-3 have the greatest
effect. Aliphatic acid anhydrides and chlorides generally react at
nitrogen, but aroyl halides give significant proportions of
O-acylated products. Limited success in converting
O-aroyl to N-aroyl isoxazolones is reported.