A facile synthesis of spiroisoxazolines: Intramolecular cyclization of 3-aryl-2-nitroacrylates promoted by titanium tetrachloride

Article abstract of DOI:10.1016/S0040-4020(99)00119-2

Titanium tetrachloride-induced cyclization of 3-(o- or m-substituted p- methoxyphenyl)-2-nitro acrylates (1) provided stereoselectively (4α,5β)-1- oxa-2-azaspiro[4, 5]deca-2,6,9-trien-8-ones (2). Ortho-substituted p- methoxyphenyl nitroacrylates gave 2 in good yield. 3-(4'-methoxy-1'- naphthyl)-2-nitroacrylate also reacted with titanium tetrachloride to give quantitatively (4α,5β)-4'-oxospiro[isoxazole(4H)5,1'(4'H)-naphthatene]. 3- (10'-methoxy-9'-anthryl)-2-nitroacrylate was converted to 10- oxospiro[anthracene-(10H)9,5'(4'H)-isoxazole].