97181-96-9Relevant academic research and scientific papers
THERMOLYSE ECLAIR DE β-ENAMINODIESTERS DERIVES DE L'ACIDE DE MELDRUM: SYNTHESE D'ENAMINONES BICYCLIQUES
Dhimane, H.,Pommelet, J. C.,Chuche, J.,Lhommet, G.,Richaud, M. G.,Haddad, M.
, p. 833 - 836 (1985)
Azabicyclic enaminones were obtained in good yield by flash vacuum pyrolysis of aminomethylene Meldrum's acid derivates.The reaction involves a -1,4 H shift from aminomethyleneketene intermediate followed by electrocyclisation of delocalized azomethine ylide.
An Efficient Synthesis of Acetylated Bicyclic Hydroxypyrroles from Cyclic Lactams via Flash-Vacuum Pyrolysis of Meldrum's Acid Derivatives
Pommelet, Jean-Claude,Dhimane, Hamid,Chuche, Josselin,Celerier, Jean-Pierre,Haddad, Mansour,Lhommet, Gerard
, p. 5680 - 5685 (2007/10/02)
The title compounds 9 were synthesized in three steps from cyclic lactams 2.After treatment of 2a-h with phosgene followed by the addition of Meldrum's acid to the chloroiminium chloride intermediates 3a-h, derivatives 4a-h were isolated in good yields.Compounds 4a-g were quantitatively converted to bicyclic enaminones 7a-g by flash-vacuum pyrolysis in the temperature range 480-600 deg C.In contrast, 4h provided 8h, the hydroxyprrole tautomer of 7h.The reaction takes place through the initial formation of (aminomethylene)ketenes 5a-h followed by a 1,4-hydrogen migration from the carbon adjacent to the nitrogen atom to the central carbon of the cumulenone.The lower temperature (480 deg C) needed for benzyl and N-carboalkoxy derivatives 4e-h in comparison with N-alkyl derivatives 4a-d (600 deg C) is correlated with gas-phase acidity of the migrating hydrogen atom.The hydroxypyrroles 8a-g, tautomers of 7a-g (78), were trapped with acetic anhydride, affording O-acetylated bicyclic hydroxypyrroles 9a-g.
A Stable Methyleneketene and the Stepwise Fragmentation of Meldrum's Acids
Lorencak, Primoz,Pommelet, J. C.,Chuche, Josselin,Wentrup, Curt
, p. 369 - 370 (2007/10/02)
Mild flash vacuum pyrolysis of the Meldrum's acid derivative (3) gives the first example of a methylenemalonic anhydride (4), which decarboxylates in solution to give the first isolable methyleneketene (5); the structures are supported by (13)C n.m.r. spectra and chemical reactions.
