99558-38-0Relevant articles and documents
PREPARATION AND SOME REACTIONS OF 4- AND 5-ARYL-4,5-DIHYDROPYRIDAZIN-3(2H)-ONES
Breukelman, Stephen P.,Meakins, G. Denis
, p. 1627 - 1636 (2007/10/02)
Efficient preparations of 4- and 5-phenyl-4,5-dihydropyridazin-3(2H)-ones have been developed, the main reactions of these compounds have been studied, and the synthetic routes have been used to give analogues with substituents in the phenyl rings.In the best synthesis of the 4-phenyldihyropyridazinone (72 percent overall yield) the product was obtained from phenylacetic acid by three simple stages.This approach was applied in preparations of the 2- and 4-hydroxyphenyl compounds and, in conjunction with a recent method for amine protection, the 4-aminophenyl analogue.A four stage synthesis starting from benzaldehyde gave the 5-phenyldihydropyridazinone in 47 percent overall yield; hydroxybenzaldehydes were similarly converted into 5-(allyloxyphenyl)dihydropyridazinones.Oxidation to phenylpyridazinones occured more readily with the 4- and 5-phenyldihydropyridazinones than with the 6-phenyl isomer.The 4- and 5-dihydropyridazinones were smoothly reduced to tetrahydropyridazinones by hydrogenation over platinum but were uneffected by palladium in the presence of hydrazine or cyclohexene.
