In 1966,Bulletin of the Chemical Society of Japan included an article by Ito, Sho; Takase, Kahei; Kawabe, Norio; Sugiyama, Hiroshi. Product Details of 5952-93-2. The article was titled 《Pyrazolotropolones and their derivatives》. The information in the text is summarized as follows:
A suspension of 10 g. 3,5,7-tribromotropolone (I, R = H, X = Br) in 150 ml. MeOH treated with excess CH2N2 in Et2O gave 2-methoxy-3,5,7-tribromotropone (I, R = Me, X = Br) (II). II (not isolated) dissolved to give an orange-red solution and this was set aside 2 days in the dark with further additions of CH2N2. The solution evaporated with evolution of HBr yielded 2.97 g. III(X = Y = Br) (IV), m. 158° (MeOH-CHCl3). IV was similarly obtained in 53.5% yield by the action of CH2N2 upon II. IV (1.247 g.) hydrogenated over 93 mg. 5% Pd-C in a mixture of 6 ml. HOAc, 60 ml. EtOAc, and 990 mg. NaOAc, the product filtered, and the filtrate distilled gave III (X = Y = H) (V), m. 135-6° (EtOAc). The structure shown, rather than the alternate structure (Va, X = H) was assigned on the basis of uv and N.M.R. spectral data. IV (93 mg.) refluxed 3 hrs. with 9 ml. 6N HCl in 20 ml. MeOH afforded on standing 64 mg. 4(or 6)-bromo-6(or 4)-chloro-7-methoxy-8(1H)-cycloheptapyrazolone, m. 143.5-4.5° (MeOH). A solution of 679 mg. IV in 150 ml. Me2CO was treated at 65-70° with 4.5 g. KMnO4 in 100 ml. aqueous solution The temperature was maintained 6 hrs., the mixture left overnight, filtered, concentrated to dryness, and the residue extracted with Me2CO to yield 126 mg. 1-methylpyrazole-4-carboxylic acid, m. 169°; Me ester m. 62-2.5°. 4-Acetyltropolone (5.0 g.) treated with 6 g. p-MeC6H4SO2NHNH2 in 30 ml. alc. gave 10.52 g. of the p-toluenesulfonylhydrazone (VI), m. 220° (decomposition). A mixture of 3 g. KOH, 5.10 g. VI, and 60 ml. alc. refluxed 7 hrs., treated with 40 ml. H2O, acidified with 6N HCl, and left overnight deposited 1.09 g. VII (R = R1 = H) (VIII), m. 211-12° (HCONMe2). The mother liquor from this preparation was concentrated, the residue was warmed with MeOH, and the sparingly soluble component was recrystallized from HCONMe2 to give IX (R = H) (X), m. 225-6°; acetate (IX, R = Ac) m. 169-70° (HOAc). The MeOH-soluble portion afforded 0.6 g. p-tolyl p-toluenethiolsulfonate, m. 75-6° (MeOH). VII (R = R1 = Me), m. 81.5-2.0° (C6H6-petr. ether), was obtained in 84.5% yield by the action of CH2N2 upon VIII. Powd. KMnO4 (2.65 g.) was added slowly to a solution of 0.53 g. VIII in 25 ml. 4N KOH, the mixture left overnight, excess KMnO4 decomposed with MeOH, and the product filtered and acidified with 6N HCl. The filtrate was concentrated in vacuo, Me2CO added to precipitate inorganic salts, and 0.4 g. 5-methylpyrazole-3,4-dicarboxylic acid (XI) was isolated from the residue obtained on concentration of the Me2CO solution The same oxidation of 0.3 g. X also gave XI. When 100 mg. 3,5-dibromotropolone was treated with CH2N2 30 mg. of product, m. 235-6° (decomposition), was obtained. The exptl. evidence available indicated either structure XII or Va (X = Br) for this compound N.M.R., ir, and uv spectral data are reported for all the compounds prepared In the part of experimental materials, we found many familiar compounds, such as Methyl 1-methyl-1H-pyrazole-4-carboxylate(cas: 5952-93-2Product Details of 5952-93-2)
Methyl 1-methyl-1H-pyrazole-4-carboxylate(cas: 5952-93-2) belongs to pyrazoles. Pyrazoles and their related multiring analogs are common elements of a wide variety of bioactive compounds. These ring structures are rare in nature. A consequence of this is that they have previously been thought to be poor moieties to include in potential new drugs. Product Details of 5952-93-2
Referemce:
Pyrazole – Wikipedia,
Pyrazoles – an overview | ScienceDirect Topics