| Abstract: | The Heterolytic Fragmentation of Benzoin-O-(carbamoyl)oximes While the known heterolytic fragmentation reactions give only three, thermal decomposition of benzoin-O-(carbamoyl)oximes results in at least four fragments: nitrile or isocyanide, carbonyl compound, CO2 and amine. This exception is due to the transformation of the nucleofugal group 3 into the unstable carbamic acid and its decomposition (s. Scheme 1). Since only the configuration of benzoin (E)-O-(carbamoyl)oximes is satisfactory for concerted reactions, we conclude that the nitrile producing fragmentation of these (E)-compounds is concerted, whereas in the isocyanide producing fragmentation of the corresponding (Z)-compounds several steps are involved. – In contrast to the benzoin-O-(carbamoyl)oximes the pyrolysis of benzil-(E)-O-(methylcarbamoyl)oxime starts with the elimination of methyl isocyanate and the following fragmentation is that of the oxime. |
