Dioximes of 1,4-Diketones

it has been shown [270] that in the KOH/DMSO system with rise of temperature from 100°C to 140°C, there is an increase in the relative amount of 2-acetyl-N-vinylpyrrole, while the ratio of the dipyrrole and methylpyridylpyrrole remains practically constant. The growth of KOH content in the system intensifies the deoxi-mation process leading to acetylpyrrole and subsequent ethyny lation of iminoaldehyde formed as a result of [3,3]-sigmatropic rearrangement that affords pyridylpyrrole. 

The application of NaOH as base (120°C, 1 h) results in formation of polymeric products. This is probably due to a lower basicity of NaOH and its more clearly 

SCHEME 1.75 The reaction of dimethylglyoxime with acetylene in the system KOH/DMSO. 

SCHEME 1.76 Formation of divinyldipyrrole from 3,4-hexanedione dioxime and acetylene. 

SCHEME 1.77 Reaction of 1,2-cyclohexanedione dioxime with acetylene. 

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