Research into analogs of pyran and related compounds
The reduction of the oximes of 2,2-dimethyl-4-chromanone (I), 2,2, 6-trimethyl-4-chromanone(II), and 2,2, 5, 7, 8-pentamethyl-6-hydroxy-4-chromanone (III) with lithium aluminum hydride has been investigated. The first of these affords the normal reduction product 2,2-dimethyl-4-amino chroman (VI), which was also obtained by catalytic hydrogenation of the oxime. The second oxime is converted into a mixture containing the 4-aminochroman (VII) and the product of reductive ring expansion, 2,2,7-trimethyl-2,3,4,5-tetrahydro-1, 5-benzoxazepine (VIII). From the oxime of III was obtained 2,2,6,8, 9-pentamethyl-7-hydroxy-2,3,4,5-tetrahydro-1,5-benzoxazepine (IX), the structure of which was confirmed by determination of the basicity constants, the NMR spectra, and the preparation of the N-benzoyl derivatives (XI).