Synthesis of 4-[Alkylsulfanyl(sulfonyl)methyl]isoxazoles and -1H-pyrazoles from 3-[(Alkylsulfanyl)methyl]- pentane-2,4-diones

Reaction of 3-(Alkylsulfanylmethyl)pentane-2,4-diones and 4-(Alkylsulfanyl)-3-(alkylsulfanylmethyl)butan-2-ones with Phenylhydrazine in the Presence of Zinc Chloride

“…Yield 0.54 g (89%). The IR and 1 H and 13 C NMR spectra of 2c were identical to those reported in [19].…”

“…were synthesized from compounds 1a-1c (2 mmol) according to the procedure described in [19] with the difference that the reactions were carried out in methanol under reflux.…”

“…4-[Alkylsulfanyl(sulfonyl)methyl]-1H-pyrazoles can be synthesized from the corresponding halogen-substituted pyrazoles [13,18]. Another method of their synthesis is based on the reaction of 3-[(alkylsulfanyl)methyl]pentane-2,4-diones with hydrazines [15,19,20]. The present study was aimed at synthesizing new functionalized 1H-pyrazoles by heterocyclization of (alkylsulfanylmethyl)-substituted mono-and 1,3-diketones with phenylhydrazine in the presence of ZnCl 2 .…”

“…While continuing studies of methods of synthesis of 4-[alkylsulfanyl(sulfonyl)methyl]-1H-pyrazoles from available dicarbonyl compounds [21][22][23][24], we have found that 3-[(alkylsulfanyl)methyl]pentane-2,4-diones 1a-1c reacted with an equimolar amount of phenyl-hydrazine in boiling methanol, as well as in ethanol or acetonitrile [19], to give up to 89% of 4-[(alkylsul fanyl)methyl]-1-phenyl-1H-pyrazoles 2a-2c (Scheme 1, Table 1). When the condensation of pentane-2,4-diones 1a-1c with phenylhydrazine was carried out in boiling methanol in the presence of 0.3-1 equiv of ZnCl 2 , apart from expected 1H-pyrazoles 2a-2c, we isolated 1-(3-methyl-1-phenyl-1H-pyrazol-4-yl)ethanone (3) in up to 56% yield.…”

“…a The reaction in ethanol was reported in[19].b The reaction mixture contained 34% of unreacted initial compound. c In a mixture of methanol and water (1:0.1).…”