106691-27-4Relevant articles and documents
Reaction of Aromatic N-Oxides with Dipolarophiles. XI. 1,3-Dipolar Cycloaddition Reaction of Pyridine N-Oxides with Tosyl Isocyanate and One-Pot Synthesis of 2-Oxooxazolo-pyridine Derivatives
Hisano, Takuzo,Harano, Kazunobu,Fukuoka, Ryuichi,Matsuoka, Toshikazu,Muraoka, Keiji,Shinohara, Ikuo
, p. 1485 - 1492 (2007/10/02)
The cycloaddition reactivity of tosyl isocyanate toward pyridine N-oxides was calculated by the CNDO/2 method using a perturbation equation, and the results indicated that the initial stage of the reaction of tosyl isocyanate with two equivalents of 3,5-dibromopyridine N-oxide in refluxing benzene gave 6-bromo-2-oxooxazolopyridine, while the use of one equivalent of 3,5-dichloropyridine N-oxide gave 6,7a-dichloro-2-oxo-3-tosyl-3a,7a-dihydrooxazolopyridine, formed from the 1,5-sigmatropic rearrangement of the corresponding primary cycloadduct.When the reaction was carried out in the presence of triethylamine in benzene, 6-halogeno-2-oxo-3-tosyloxazolopyridine was isolated.The observed activation parameters, as well as the small solvent effects, may be interpreted in terms of a concerted pathway.The reaction should be very valuable as a one-pot synthesis of 2-oxooxazolopyridines, which are opyridine analogues of 5-chloro-2-benzoxazolinone.Keywords - 3,5-dihalogenopyridine N-oxide; tosyl isocyanate; 6-halogeno-2-oxooxazolopyridine; kinetics; frontier molecular orbital; solvent effect; 1,3-dipolar cycloaddition; detosylation
