(Cyanovinyl)ketenes from azafulvenones. An apparent retro-Wolff rearrangement

@article{Qiao1996CyanovinylketenesFA,
  title={(Cyanovinyl)ketenes from azafulvenones. An apparent retro-Wolff rearrangement},
  author={G. Qiao and W. Meutermans and M. W. Wong and M. Tr{\"a}ubel and C. Wentrup},
  journal={Journal of the American Chemical Society},
  year={1996},
  volume={118},
  pages={3852-3861}
}
Flash vacuum pyrolyses or pulsed pyrolysis of azole esters 1b and 20 and their carboxylic acids 1a and 19 or acid chloride 1c give five-membered ring ketenes (azafulvenones) 2 and 24 which dimerize to diketopiperazines 3 and 21 but also undergo efficient rearrangement to (cyanovinyl)- and (o-cyanophenyl)ketene (6 and 27). The same products are obtained by elimination of alcohol from esters of these (cyanovinyl)ketenes. Both types of ketenes are observed directly by IR spectroscopy and are… Expand
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