Unexpected regioselectivity in cycloisomerization of 2-alkynyl-3-nitro- thiophenes
The intramolecular cycloizomerization of 2-alkynyl-3-nitrothiophenes was catalyzed by AuCl3 or CF3CO2Ag to produce the corresponding thieno[3,2-c]isoxazoles bearing carbonyl functionality in position 3 instead of expected