Photocyclization of Coumarinoyl Enamides Revisited: [2+2+2]Cycloreversion/Cycloaddition Mechanism

The major and minor products for photocyclization of coumarinoyl enamides were identified. The controlled and intermediate-trapping experiments indicate that the formation of the minor isomer involved a stepwise, radical [2+2+2]...

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.

B31− and B32−: chiral quasi-planar boron clusters

Chiral boat-like B31− (C1, I and II) and B32− (C2, VI and VII) are characterized in a joint experimental and theoretical investigation, with a chair-like intermediate (Ci, VIII) also observed for B32− as a minor isomer.