83297-09-0Relevant articles and documents
The Reaction of Meldrum's Acid with α-Dicarbonyl Monohydrazones: A New Synthesis of Pyridazin-3-ones
McNab, Hamish,Stobie, Ian
, p. 1845 - 1854 (2007/10/02)
Treatment of the monohydrazones of α-dicarbonyl compounds with Meldrum's acid gives the condensation products (13)-(19) under standard conditions.Reaction of pyruvaldehyde 2-phenylhydrazone or 2-t-butylhydrazone with Meldrum's acid at 80 deg C gives the corresponding 2-substituted-2,3-dihydro-6-methyl-3-oxo-pyridazine-4-carboxylic acids (29) and (30).Cyclisation of the other N-monosubstituted condensation products (13), (14), (16), (18), and (19) to 3-oxopyridazine-4-carboxylic acids (31)-(35) can be effected under basic conditions.Gas-phase pyrolysis of the N-aryl derivatives (13)-(16) at 550 deg C and 10E-2 Torr gives N-arylpyridazin-3-ones (38)-(41) while the N-t-butyl derivatives (18) and (19) at 750 deg C and 10E-2 Torr give N-unsubstituted pyridazin-3-ones (44) and (45) by additional loss of 2-methylpropene. 2-t-Butylpyridazin-3-ones (42) and (43) can be isolated from the same precursors under milder conditions (500 deg C and 10E-2 Torr).Pyrolysis of the N,N-dimethyl derivative (17) gave only polymeric material.
