The Heterolytic Fragmentation of Benzoin-O-(carbamoyl)oximes

Article abstract of DOI:10.1002/hlca.19800630717

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 following fragmentation is that of the oxime.