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Synlett
Volumn , Issue 1, 2009, Pages 92-96
General synthetic approach to 4-substituted 2,3-dihydrofuro[2,3-b]pyridines and 5-substituted 3,4-dihydro-2H-pyrano[2,3-b]pyridines
Author keywords

Cycloaddition; Dihydrofuro 2,3 b pyridines; Dihydropyrano 2,3 b pyridines; Inverse electron demand Diels Alder reactions; Microwave activation
Indexed keywords

EID: 62349117573     PISSN: 09365214     EISSN: 14372096     Source Type: Journal    
DOI: 10.1055/s-0028-1087485     Document Type: Article
Times cited : (12)
References (34)
  • 5
    • 33646136917 scopus 로고    scopus 로고
    • Weinreb, S. M, Ed, Thieme: NewYork
    • (b) Lindsley, C. W.; Layton, M. E. In Science of Synthesis, Vol. 17; Weinreb, S. M., Ed.; Thieme: NewYork, 2003, 357-447.
    • (2003) Science of Synthesis , vol.17 , pp. 357-447
    • Lindsley, C.W.1    Layton, M.E.2
  • 30
    • 62349084355 scopus 로고    scopus 로고
    • General Procedure for the Intramolecular Inverse-Electron-Demand Diels-Alder Reaction for Compounds 10-13 Bromoalkyne 5, 6 or 8, 9 (0.33 mmol) was dissolved in chlorobenzene (2 mL) and heated at 180-200°C under microwave irradiation (3-6 bar of pressure can be involved, The reaction was monitored by TLC (for reaction time and temperature, see Table 1, After complete conversion of the starting material, the reaction was purified by chromatography (eluent: PE-EtOAc, 8:2) to give the desired products 10-13. 4-Bromo-2,3-dihydrofuro[2,3-b]pyridine (10) Yield 82, as a colorless oil. IR (KBr, 3000, 2908, 1577, 945, 713, 698, 614 cm -1. 1H NMR (250 MHz, CDCl3, δ, 7.78 (d, J, 5.6 Hz, 1 H, 6.91 (d, J, 5.6 Hz, 1 H, 4.64 (t, J, 8.8 Hz, 2 H, 3.23 (t, J, 8.8 Hz, 2 H, 13C NMR (62.9 MHz, CDCl3, δ, 168.4 (C, 147.2 (CH, 129.9 (C, 121.6 C, 119
    • +: 199.9709; found: 199.9709.
  • 31
    • 62349101575 scopus 로고    scopus 로고
    • General Procedure for the Suzuki Cross-Coupling Reaction for Compounds 14-17 A solution of compounds 10-13 (0.73 mmol) in ethylene glycol dimethyl ether (5 mL, freshly distilled and degassed) under argon was treated with furan-2-boronic acid. A solution of Na2CO3 (154 mg, 1.45 mmol) in H2O (2.5 mL) was added before adding Pd(PPh 3)4 (42 mg, 0.036 mmol, and the mixture was stirred vigorously at 75°C and monitored by TLC (for reaction time, see Table 2, After complete conversion of the starting material, the mixture was diluted with EtOAc and filtered through Celite. The filtrate was washed with brine, dried over MgSO4, evaporated, and purified by column chromatography (eluent: PE-EtOAc) to give the corresponding compounds 14-17. 4-Fur-2-yl-2,3-dihydrofuro[2,3-b]pyridine (14) Yield 74, as a yellow solid; mp 93-95°C. IR KBr, 2971, 1605, 1451, 1229, 1125, 1025, 807 cm-1
    • +: 188.0694; found: 188.0704.
  • 32
    • 62349138828 scopus 로고    scopus 로고
    • General Procedure for the Stille Cross-Coupling Reaction for Compounds 18-21 To a suspension of freshly prepared Pd(PPh3)4 (25 mg, 0018 mmol) and LiCl (42 mg, 0.99 mmol) in dry DMF was added a solution of compounds 14-17 (0.36 mmol) and tributyl-2-propenylstannane (169 μL, 0.54 mmol) in dry DMF under argon. After 2-3 h (see Table 3) under reflux at 90°C, the reaction mixture was cooled to r.t. and quenched with brine (10 mL, The aqueous layer was extracted with EtOAc (2 x 20 mL, the organic phase were collected, dried over MgSO4, and the solvents were removed under reduced pressure. Flash column chromatography (eluent: PE-EtOAc, 9:1) of the crude gave the desired products 18-21. 4-Allyl-2,3-dihydrofuro[2,3-b]pyridine (23) Yield 62, as a yellow oil. IR (KBr, 2976, 2906, 1639, 1608, 1588, 1227 cm-1. 1H NMR (250 MHz, CDCl3, δ, 7.90 (d, J, 5.3 Hz, 1 H, 6.62 d
    • +: 162.0906; found: 1162.0919.
  • 33
    • 62349104503 scopus 로고    scopus 로고
    • General Procedure for the Sonogashira Cross-Coupling Reaction for Compounds 22-25 A solution of the aryl bromide 12 or 13 (1.11 mmol) in anhyd ethylene glycol dimethyl ether (2.0 mL) was treated with the appropriate alkyne (1.11 mmol) and Et3N (3 mL, After 5 min, CuI (0.021 g, 0.11 mmol) and Pd(PPh3)2Cl2 (0.04 mg, 0.06 mmol) were added. The mixture was then stirred vigorously at 60°C and monitored by TLC. After 24 h, the mixture was diluted with EtOAc and filtered through Celite. The filtrate was washed with brine, and dried over MgSO 4, evaporated and purified by column chromatography (eluent: PE-EtOAc, 9:1) to give the corresponding compounds 22-25. 7-Phenyl-4-[2-(trimethylsilyl)ethynyl]-3,4-dihydro-2H-pyrano[2, 3-b]pyridine (25) Yield 44, as a dark oil. IR (KBr, 3049, 2248, 1580, 1428, 1352, 1233, 904, 742 cm-1. 1H NMR 250 MHz, CDCl3
    • +: 308.1468; found: 308.1471.
  • 34
    • 62349091472 scopus 로고    scopus 로고
    • General Procedure for the Stille Reaction with 3-Bromopyridine Compounds 32 and 33 were prepared in 70% yield, according to the procedure used for the synthesis of 18-21. The purification was carried out by flash chromatography over SiO2 (eluent: PE-EtOAc, 8:2 to 6:4, 7-Phenyl-5-pyrid-3-yl-3,4-dihydro-2H-pyrano[2,3- b]pyridine (33) Yield 68, as a clear yellow oil. IR (KBr, 3160, 2970, 2253, 1574, 1444, 1002, 906, 740 cm-1. 1H NMR (250 MHz, CDCl3, δ, 8.64 (s, 1 H, 8.63 (d, J, 1.2 Hz, 1 H, 8.00 (d, J, 6.5 Hz, 2 H, 7.68 (dd, J, 1.2 Hz, J′, 5.7 Hz, 1 H, 7.43-7.23 (m, 4 H, 7.23 (s, 1 H, 4.40 (t, J, 5.0 Hz, 2 H, 2.67 (t, J, 6.2 Hz, 2 H, 2.00-1.94 (m, 2 H, 13C NMR (62.9 MHz, CDCl3, δ, 161.3 (C, 154.3 (C, 149.5 (CH, 149.3 (CH, 148.8 (C, 138.3 (C, 136.0 (CH, 134.7 C, 129.1
    • +: 289.1350; found: 289.1341.

* 이 정보는 Elsevier사의 SCOPUS DB에서 KISTI가 분석하여 추출한 것입니다.