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Volumn 50, Issue 13, 2009, Pages 1392-1394

DAST promotes the synthesis of new 5-(trifluoromethyl)-3-(1,1-difluoroethan-2-yl)-1H-pyrazoles

Author keywords

[No Author keywords available]

Indexed keywords

1,1,3,3 TETRAMETHOXYBUTANE; 4,6,6 TRIMETHOXY 1,1,1 TRIFLUOROHEX 3 EN 2 ONE; ACETAL DERIVATIVE; ALDEHYDE; BUTANE; DIETHYLAMINOSULFUR TRIFLUORIDE; FLUORIDE; HYDRAZINE DERIVATIVE; PYRAZOLE DERIVATIVE; TRIFLUOROACETIC ACID; UNCLASSIFIED DRUG;

EID: 59849113451     PISSN: 00404039     EISSN: None     Source Type: Journal    
DOI: 10.1016/j.tetlet.2009.01.005     Document Type: Article
Times cited : (22)

References (37)
  • 28
    • 59849126218 scopus 로고    scopus 로고
    • note
    • Synthesis of 4,6,6-trimethoxy-1,1,1-trifluorohex-3-en-2-one (1). General procedure: To an ice-cold stirred mixture of 1,1,3,3-tetramethoxybutane (30 mmol), pyridine (60 mmol), and anhydrous chloroform (30 mL) was added dropwise pure trifluoroacetic anhydride (60 mmol), and after completion of the slow addition, the mixture was stirred for 24 more hours at room temperature. Then, the mixture was washed with aqueous solution of hydrochloric acid 0.1 M (3 × 15 mL) and water (2 × 15 mL), and was dried with magnesium sulfate. The solvent was evaporated to give the practically pure products 3. The pure compound was obtained by distillation under reduced pressure (65% yield).
  • 29
    • 59849128905 scopus 로고    scopus 로고
    • note
    • 3, J = 292), 101.5 (C-6), 92.2 (C-3), 56.6 (C-6a-b), 53.1 (C-4a), 37.6 (C-5).MS: m/z (%) = 211 (66), 179 (71), 141 (36), 75 (100).Anal. Calcd: C, 44.63; H, 5.41. Found: C, 44.85; H, 5.13.
  • 30
    • 59849120892 scopus 로고    scopus 로고
    • note
    • Synthesis of 3-(1,1-dimethoxyethan-2-yl)-5-hydroxy-5-trifluoromethyl-4,5-dihydro-1H-p yrazole (2a-b). General procedure: A stirred solution of 4,6,6-trimethoxy-1,1,1-trifluorohex-3-en-2-one (1) (2 mmol) with hydrazine (2 mmol) in 15 mL of dry ethanol was stirred at 80 °C for 4 h (2b) and 20 h (2a). After the reaction time, the solvent was removed under reduced pressure, and the products were dried under vacuum, and isolated as a solid (2a) and an oil (2b) (yields 90-97%).
  • 31
    • 59849094304 scopus 로고    scopus 로고
    • note
    • 2J = 33, C-5), 52.9 (C-7a-b), 46.3 (C-4), 32.2 (C-6).MS: m/z (%) = 305 (20), 95 (97), 75 (100), 47 (47).Anal. Calcd: C, 46.43; H, 4.50; N, 8.33. Found: C, 46.95; H, 4.46; N, 8.49.Melting points and yields of new compounds 2: Compd. [Mp (°C), Yield (%)]: Compound 2a [120-122, 97]; Compound 2b [oil, 90].Melting points and yields of new compounds 2: Compd. [Mp (°C), Yield (%)]: Compound 2a [(120-122), 97]; 2b [(oil), 90].
  • 32
    • 59849103922 scopus 로고    scopus 로고
    • note
    • Synthesis of 3-(1,1-dimethoxyethan-2-yl)-5-trifluoromethyl-1H-pyrazole (3a-b). General procedure: A solution of 3-(1,1-dimethoxyethan-2-yl)-5-hydroxy-5-trifluoromethyl-4,5-dihydro-1H-p yrazole (2a-b) (2.6 mmol) and pyridine (33.8 mmol) in 50 mL of benzene was cooled to 0 °C, and thionyl chloride (16.8 mmol) diluted in 25 mL of benzene was added dropwise over 10 min. The solution was stirred for an additional 30 min, during which time the temperature was allowed to rise to 20 °C. The mixture was then heated under reflux (bath temperature 80 °C) for 1 h, and was then filtered to remove the pyridine hydrochloride at room temperature. The solution was washed twice with water and dried over sodium sulfate. The solvent was evaporated, obtaining dark oils as pure compounds (3a-b). (yields 75-85%).
  • 33
    • 59849096139 scopus 로고    scopus 로고
    • note
    • 3, J = 269 Hz), 113.9 (C-4′), 112.5 (C-4), 102.8 (C-7), 53.4 (C-7a-b), 32.1 (C-6).MS: m/z (%) = 287 (20), 149 (12), 95 (93), 75 (100).Anal. Calcd: C, 49.06; H, 4.12; N, 8.80. Found: C, 48.91; H, 4.22; N, 9.19.Yields of new compounds 3: Compd. [Mp (°C), Yield (%)]: Compound 3a [oil, 75]; Compound 3b [oil, 85].
  • 34
    • 59849114510 scopus 로고    scopus 로고
    • note
    • Synthesis of 3-(formylmethyl)-5-trifluoromethyl-1H-pyrazole (4a-b). General procedure: A stirred solution of 3-(1,1-dimethoxyethan-2-yl)-5-trifluoromethyl-1H-pyrazole (3a-b) (2 mmol) in 8 mL of chloroform is added to an 4 mL aqueous solution of trifluoroacetic acid (1:1). The solution was stirred for 4 h at 30 °C, and was then washed twice with water and dried over sodium sulfate. The solvent was evaporated, obtaining a yellow solid (4a) or a dark oil (4b), as pure compounds.
  • 35
    • 59849091612 scopus 로고    scopus 로고
    • note
    • 3, J = 269), 113.8 (C-4′), 112.7 (C-4), 42.5 (C-6).MS: m/z (%) = 244 (10), 216 (4), 95 (100).Anal. Calcd: C, 48.54; H, 2.59; N, 10.29. Found: C, 48.63; H, 2.78; N, 10.04.Melting points and yields of new compounds 4: Compd. [Mp (°C), Yield (%)]: Compound 4a [123-124, 55]; Compound 4b [oil, 65].
  • 36
    • 59849119937 scopus 로고    scopus 로고
    • note
    • 3, and filtered. The solvent was evaporated, obtaining a yellow solid (5a) and dark oil (5b). Compound 5a was recrystallized from diethylether and compound 5b was purified by chromatography on silica, using an ethyl acetate and hexane mixture.
  • 37
    • 59849104125 scopus 로고    scopus 로고
    • note
    • +, 5), 266 (70), 188 (5), 95 (100).Anal. Calcd: C, 44.91; H, 2.40; N, 9.52. Found: C, 44.63; H, 2.51; N, 9.47.Melting points and yields of new compounds 5: Compd. [Mp (°C), Yield (%)]: Compound 5a [128-130, 55]; Compound 5b [oil, 60].


* 이 정보는 Elsevier사의 SCOPUS DB에서 KISTI가 분석하여 추출한 것입니다.