- PYRIDAZINES XXIV. APPLICATION OF RADICALIC ETHOXYCARBONYLATION TO THE SYNTHESIS OF PYRIDAZINE MONO- AND POLYCARBOXYLIC ACID ESTERS
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Reactivity of pyridazines 1, 2, 3, 16 towards ethoxycarbonylradical (generated by redox decomposition of oxyhydroperoxyde of ethylpyruvate) was studied.Application of this type of homolytic substitution for synthesis of hitherto not accessible pyridazine carboxylic acid esters 6, 8, 9, 12, 13, 14, 15, 17 is demonstrated.In addition improved synthesis of diethyl 4,5-pyridazinedicarboxylate (5) is proposed.
- Heinisch, Gottfried,Loetsch, Gerhard
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p. 1199 - 1206
(2007/10/02)
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- SYNTHESES AND REACTIONS OF PYRIDAZINE DERIVATIVES XX STUDIES ON THE RADICAL METHYLATION OF THE 1,2-DIAZINE SYSTEM
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Protonated pyridazines (1,2,3) on reaction with methyl radical (generated by oxidative decarboxylation of acetic acid or by redox reaction of t-BuOOH/FeSO4*7H2O) are shown mainly to be attacked at positions β to the nitrogen atoms.However, formation of compounds 2, 4, 5, 6, 8, 9 and 10 indicates lower degree of regioselectivity compared with homolytic benzylation or acylation of the 1,2-diazine system.Synthesis of ethyl 5-styryl-4-pyridazinecarboxylates(13,14) was achieved by homolytic methylation of ethyl 4-pyridazinecarboxylate(11) followed by condensation with aromatic carbaldehydes.
- Heinisch, Gottfried,Loutsch, Gerhard
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p. 1395 - 1402
(2007/10/02)
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