(Hive Bee)
09-13-03 20:14
No 458895
(Rated as: excellent)
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)
Abstract
O,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 NaHCO3 and saturated with NaCl. The solution was extracted with CH2Cl2 (400mL), dried over Na2SO4, and concentrated, and the residue was flash-chromatograped (CH2Cl2: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_753
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(Chief Bee)
09-13-03 22:07
No 458900
Nice, it reminds me a little of this one:
Post 76334 (Rhodium: "New synthesis of Phenyl-2-propanones", Novel Discourse)
Post 210023 (Scooby_Doo: "Re: New synthesis of Phenyl-2-propanones", Novel Discourse)