Working with ethanol (white solid), m.p: 225.5 to 227.five , 1H NMR (400 MHz, d6-DMSO) H: 1.40 (s, 9H, methyl protons of Boc), two.49 (t, q = 1.Purified by recrystallisation utilizing ethanol (white solid), m.p: 156.two to 157.five , 1H NMR (400 MHz, d6-DMSO) H: six.07 (s, 1H at C-4), 7.31 to 7.40 (m, 3H, aryl protons), 7.48 (t, J = 8.0 Hz, 2H, aryl protons), 7.07 to 7.33 (m, 4H, aryl protons), 7.83 to 7.93 (m, 4H, aryl protons), 11.94 (bs, 1H, -OH proton at C-5); 13C NMR (100 MHz,Ragavan et al. Organic and Medicinal Chemistry Letters 2013, 3:six http://orgmedchemlett/content/3/1/Page 13 ofd6-DMSO): 85.57 (C-4), 116.01, 116.24, 123.52, 123.60, 126.10, 126.96, 127.25, 127.94, 129.42, 132.92, 135.74, 139.91, 140.17 (aryl carbons), 149.69 (C-3), 154.18, 159.05 (aryl carbons), 161.46 (C-5). MS calculated for C21H15FN2O: 330.55. Found: 329.0 (M-1).3-Ethyl-4-methyl-1H-pyrazol-5(4H)-one (21)ring), 85.78 (C-4), 146.75 (C-3), 160.78 (C-5). MS calculated for C6H8N2O: 124.14. Found: 124.9 (M+).3-Isopropyl-1H-pyrazol-5(4H)-one (26)Purified by recrystallisation working with ethanol (white strong), m.p: 233.four to 234.1 , 1H NMR (400 MHz, d6-DMSO) H: 1.07 (t, J = 7.64 Hz, 3H, methyl protons of ethyl group), 1.72 (s, 3H, methyl at C-4), 2.40 (q, J = 7.6 Hz, 2H, methylene protons of ethyl group), 9.50 (bs, 1H, -OH proton), ten.05 (bs, 1H, -OH proton); 13C NMR (100 MHz, d6-DMSO): 11.34 (methyl carbon of ethyl group), 18.35 (methyl group at C-4), 22.99 (methylene carbon of ethyl group), 99.73 (C-4), 147.27 (C-3), 164.86 (C-5). MS calculated for C6H10N2O: 126.15. Identified: 128.0 (M + two).4-Ethyl-3-phenyl-1H-pyrazol-5(4H)-one (23)Purified by recrystallisation applying ethanol, m.p: 198.two to 199.four (white strong).1H NMR (400 MHz, d6-DMSO) H: 1.13 (d, J = six.92 Hz, 6H), 2.79 to 2.72 (m, 1H), five.20 (s, 1H), 9.32 (bs, 1H, -NH proton), 11.50 (bs, 1H, -OH proton); 13C NMR (100 MHz, d6-DMSO): 22.24 (carbon of two CH3 of iso-propyl), 25.69 (methine carbon of iso-propyl), 86.22 (C-4), 150.39 (C-3), 160.75 (C-5). MS calculated for C6H10N2O: 126.15. Located: 126.9 (M+).Purified by recrystallisation applying ethanol (white solid), m.p: 88.3 to 89.1 . 1H NMR (400 MHz, d6-DMSO) H: 1.15 (t, J = 7.6 Hz, 3H, protons of methyl group), two.64 (q, J = 7.six Hz, 2H, protons of methylene group), 7.17 to 7.13 (m, 1H), 7.41 to 7.32 (m, 3H), 10.00 (bs, 2H, -OH and -NH protons); 13C NMR (one hundred MHz, d6DMSO): 13.57 (methyl carbon of ethyl group), 19.ten (methylene carbon of ethyl group), 102.27 (C-4), 125.34 (ipso), 128.12 (ortho), 128.60 (meta), 133.1932384-22-9 supplier 88 (para), 142.549531-11-5 uses 49 (C-3), 159.PMID:24282960 20 (C-5). MS calculated for C11H12N2O: 188.22. Identified: 188.8 (M+).3-Cyclohexyl-4-methyl-1H-pyrazol-5(4H)-one (24)Purified by recrystallisation utilizing ethanol (white solid), m.p: 205.4 to 206.2 . 1H NMR (400 MHz, d6-DMSO) H: 1.25 to 1.28 (m, 1H, proton of cyclohexyl ring) 1.32 to 1.40 (m, 4H, protons of cyclohexyl ring), 1.66 to 1.76 (m, 8H, five protons of cyclohexyl ring and protons of methyl group), two.40 to 2.50 (m, 1H, proton of cyclohexyl ring), 9.50 (bs, 1H, -NH proton) 10.52 (bs, 1H, -OH proton); 13C NMR (100 MHz, d6-DMSO): six.91 (carbon of methyl group), 26.01, 26.53, 31.91, 36.42 (carbons of cyclohexyl ring), 94.38 (C-4), 145.71 (C-3), 160.12 (C-5). MS calculated for C10H16N2O2: 180.24. Discovered: 180.8 (M+).3-Cyclopropyl-1H-pyrazol-5(4H)-one (25)Conclusions The -keto esters from ethyl chloroformate was successfully attempted, as well as the created method is very simple, rapidly and applicable to the ketones having the alkyl halogens, safeguarding groups like Boc and Cb.