Straightforward transformation of isoxazoles into pyrazoles: renewed and improved

Supramolecular Columnar Liquid Crystals with Tapered‐Shape Simple Pyrazoles Obtained by Efficient Henry/Michael Reactions

“…In addition, the isoxazole byproduct could be isolated and transformed into the desired pyrazole in af urthers tep ( Figure S2 in the Supporting Information) by heatingw ith hydrazine hydratea nd Raney nickel. [20] Pyrazoles werec haracterizedb ye lemental analysis, NMR spectroscopy,a nd mass spectrometry and the data are consistentw ith the proposedc hemical structures (see the Experimental Section).…”

Synthesis of 3,5-Disubstituted Isoxazoles and Isoxazolines in Deep Eutectic Solvents

“…The combination of aromatic aldehydes and aliphatic alkenes gave the corresponding product with moderate yield (entries 9). 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 Once the scope of the reaction was studied, a ring opening reaction [72][73][74][75][76][77][78][79] was carried out using 0.5 equivalents of Mo(CO) 6 and starting from the previously obtained isoxazoles 3 ( Table 4). The reaction took place with good yields when the substituents of the isoxazole were aromatic, independently of the electronic nature of the substituents in these rings (entries 1-3).…”

The conversion of isothiazoles into pyrazoles using hydrazine

“…The analogous transformation of isoxazoles into pyrazoles using arylhydrazines [18][19][20][21][22][23][24][25][26][27][28][29][30][31][32][33][34] or alkylhydrazines 35 is well documented. Furthermore the transformations of isoxazolium salts, 36 isoxazolidin-2-yl, 37 isoxazolidin-5-ones, 38 isoxazol-4-one oximes 39,40 and isoxazole-4,5-diones 41 into pyrazoles have been reported.…”