1593175-40-6Relevant articles and documents
Cyclocondensation of hydroxylamine with 1,3-bis(het)arylmonothio 1,3-diketones and 1,3-bis(het)aryl-3-(methylthio)-2-propenones: Synthesis of 3,5-bis(het)arylisoxazoles with complementary regioselectivity
Raghava, Byregowda,Parameshwarappa, Gangajji,Acharya, Anand,Swaroop, Toreshettahally R.,Rangappa, Kanchugarakoppal S.,Ila, Hiriyakkanavar
, p. 1882 - 1892 (2014/04/03)
Efficient routes for the regioselective synthesis of 3,5-bis(het) arylisoxazoles with complementary regioselectivity have been developed. The methods involve the cyclocondensation of hydroxylamine hydrochloride with either 1,3-bis(het)aryl-monothio-substituted 1,3-diketones 1 or with 3-methylthio-1,3-bis(het)aryl-2-propenones 2 under various reaction conditions. In the first protocol, diketones 1 were treated with hydroxylamine hydrochloride in the presence of sodium acetate/acetic acid (pH 2.2) in refluxing ethanol/benzene to give 3,5-bis(het)arylisoxazoles 5, in which the het(aryl) moiety attached to thiocarbonyl group of the monothio-substituted 1,3-diketones is installed at the 3-position. On the other hand, the reaction of hydroxylamine hydrochloride with 3-(methylthio)-1,3-bis(het)aryl-2-propenones 2 in the presence of barium hydroxide in refluxing ethanol gave 3,5-bis(het) arylisoxazoles 6 with complementary regioselectivity in high yields. A probable mechanism for the formation of regioisomeric isoxazoles 5 and 6 from precursors 1 and 2 has been suggested.
