Reactions of O,O-Diprotonated Nitro Olefins with Benzenes. Formations of Phenylacetones, 4H-1,2-Benzoxazines and Biarylacetone Oximes Tetrahedron 46 (21), 7539 - 7555 (1990)AbstractO,O-Diprotonated nitro olefins undergo three alternative electrophilic reactions which yield
alpha-phenylacetone, 4H-1,2-benzoxazines and biphenylactone oximes depending on the reaction conditions (temperature and time) and aromatic substrates. Although these reactions are seemingly divergent, a common intermediate of a phenylated protonated
aci-nitro species, derived from the dication, is postulated to be involved in the reactions. Futhermore, the formation of benzoxazines and biphenylacetone oximes can be interpreted in terms of participation of novel chemical species with phenylethylene diction character derived from the common intermediate.
Acid-Catalyzed Reactions of 2-Nitropropene with Benzene at a Low Temperature. Formation of Phenylacetone
4e(A) Methanol and Water Work-up:A solution of 2-nitropropene (
2e) (299mg) in benzene (total amount of benzene used was 30 equiv.) was added to a well stirred mixture of TFSA (10 equiv. with respect to
2e) and benzene with methylene chloride as a co-solvent (30 equiv. with respect to
2e cooled to -40 °C in a dry ice-acetone bath. The reaction mixture was poured after 1 min into a large excess of dry methanol (100mL), cooled to -78 °C, with vigorous stirring. After being warmed to ambient temperature (10-15 min), the resultant yellow solution was diluted with water (150mL), neutralized with powdered NaHCO
3 and saturated with NaCl. The solution was extracted with CH
2Cl
2 (400mL), dried over Na
2SO
4, and concentrated, and the residue was flash-chromatograped (CH
2Cl
2:n-hexane 12:7) to give pure 3-phenylpropan-2-one (
4e), 392mg (85%), as a colorless oil.
See the full text PDF for more details
http://www.bomber.co.nz/bjp/tet46_21_7539.pdf
