Synthesis of Some Alicyclic Oximes and Study of the Expected Conformational Isomerism

Five alicyclic oximes 1 – 5 have been readily synthesized in moderate to good yields. These oximes were obtained through a reaction between the hydroxylamine hydrochloride and a number of alicyclic ketones (cylobutanone, cyclopentanone, cyclohexanone, cycloheptanone and cyclooctanone) under mild reaction conditions. The spectroscopic data confirmed the formation of the first four oximes 1 – 4 as single conformational isomers. However, the cyclooctanone oxime 5 was obtained as a mixture of two conformational isomers with 81% for the major and only 19% for the minor isomer. Such finding could be an indication for the relationship between the increase of the ring size of the oxime and the raising possibility of the formation of conformational isomers as the flexibility of the ring increases.