Abstracts Chemistry

Deamination of 1-amino-4-bromo-7, 7-dimethylbicyclo[2.2.1]heptan-2-ol: A cyclic hydroxamic acid from 1,3-cyclo-hexanedione and β-nitrostyrene

by Thean-Chit Ooi

Typescript. Bibliography: leaves 111-115. ix, 115 l illus PART I: Deamination of l-amino-4-bromo-7,7-dimethylbicyclo_ [2.2.1]heptan-2-ol (1) with nitrous acid formed 4-bromo-5, 5-dimethylbicyclo[2.1.1]hexane-l-carboxaldehyde (2). The structure of 2 was elucidated with infrared and nmr spectra. The corresponding carboxylic acid, semicarbazone, and p-toluenesulfonylhydrazone derivatives of 2 were prepared. The ring contraction during the deamination of 1 is similar to that of l-amino-3,3-dimethylbicyclo[2.2.1]heptan-2-ol (3), which formed 5,5-dimethylbicyclo[2.1.1]hexane-l-carboxaldehyde (4). Compounds 1 and 3 are different in the configuration of the hydroxyl groups and the substitution feature at C-3. Therefore, the successful deamination of 1 and 3 to the bicyclo[2.1.1]hexane derivatives demonstrates that the deamination of l-aminobicyclo[2.2.1]heptan-2-ols may be of general utility. During the ring contraction, the migrating group is anti-coplanar to the leaving group. PART II: Condensation of β-nitrostyrene with 1,3-cyclohexanedione in the presence of sodium methoxide did not yield a normal Michael addition product. The product was proved, with the support of spectral data, to be N-hydroxy-3-phenyl-4,5,6,7-tetrahydrooxindol-4-one (5). The acetyl derivative of 5, which gave a band in the infrared spectrum that is characteristic of an ester, ruled out the isomeric structure 6 as an alternative structure for 5. Upon hydrolysis, compound 5 could be converted into keto acid Z, from which a known compound, 2-phenyloctanedioic acid, could be obtained through Wolff-Kishner reduction. Hydrogenation of 5 over Raney nickel catalyst produced 3phenyl- 2,3,4,5,6,7-hexahydroindol-4-one (9), which was then dehydrogenated with Raney nickel in hot ethanol to form 3phenyl- 4,5,6,7-tetrahydroindol-4-one (2). Structures 8 and 9 were fully elucidated, and an authentic sample of 9 was synthesized. Stetter and Hoehne proposed oxazine 10 as the structure of the condensation product. This structure is reassigned as 5.