A simple synthetic method for fluorine-containing 4H-pyrano[3,2- d]isoxazoles and 4-cyanoethyl-isoxazoles from 5-trifluoroacetyl-2-methoxy- 3,4-dihydro-2H-pyran with hydroxylamine hydrochloride

Article abstract of DOI:10.3987/COM-98-S(H)65

5-Trifluoroacetyl-2-methoxy-3,4-dihydro-2H-pyran (1), prepared from 2- methoxy-3,4-dihydro-2H-pyran with trifluoroacetic anhydride, reacted cleanly with hydroxylamine hydrochloride in alcohol to give fluorine-containing 4H- pyrano[3,2-d]isoxazoles (2a-g) or 4-cyanoethyldihydroisoxazoles (3) selectively in moderate to high yields. Further conversion of 3 into 4- cyanoethylisoxazoles (4) was also described.