Potassium Carbonate → 4-ethyl-8-methoxy-1H-pyrano[3,4-c]pyridine

HRID 357509Notizen

Reaktionsgleichung

Reaktionsgleichung von HRID 357509
[CH:1](=[C:3]1[C:12]2[C:7](=[C:8]([O:13][CH3:14])[N:9]=[CH:10][CH:11]=2)[CH2:6][O:5][CH2:4]1)[CH3:2].C(=O)([O-])[O-].[K+].[K+]>C(O)CC.C1C=CC(P(C2C=CC=CC=2)C2C=CC=CC=2)=CC=1.C1C=CC(P(C2C=CC=CC=2)C2C=CC=CC=2)=CC=1.C1C=CC(P(C2C=CC=CC=2)C2C=CC=CC=2)=CC=1.[Cl-].[Rh]>[CH2:1]([C:3]1[C:12]2[C:7](=[C:8]([O:13][CH3:14])[N:9]=[CH:10][CH:11]=2)[CH2:6][O:5][CH:4]=1)[CH3:2]

Komponenten

5

Edukt 2

HCID 11430Potassium CarbonateHCID 540824384-ethylidene-8-methoxy-3,4-dihydro-1H-pyrano[3,4-c]pyridine

Produkt 1

HCID 106315694-ethyl-8-methoxy-1H-pyrano[3,4-c]pyridine

Reagenzien, Katalysatoren, Lösungsmittel 2

HCID 84599Chlorotris(triphenylphosphine)rhodium(I)Katalysator3×HCID 10311-PropanolLösungsmittel

Versuchsvorschrift

A warmed solution of 4-ethylidene-8-methoxy-3,4-dihydro-1H-pyrano[3,4-c]pyridine, prepared as in example 3 (0.35 g, 1.83 mmol) in 30 mL of n-propanol is purged with a stream of nitrogen for 20 minutes prior to the addition of tris(triphenylphosphine)rhodium(I) chloride (0.025 g, 0.027 mmol). The reaction mixture is stirred at reflux for 15 hours under nitrogen and again treated with tris(triphenylphosphine)rhodium(I) chloride (0.025 g). After 2 hr, the flask is charged with potassium carbonate (0.50 g, 3.60 mmol), and heated for 2 hr. The mixture is then treated with tris(triphenylphosphine)rhodium(I) chloride (0.025 g). The mixture is heated to reflux for an additional 2 hr, filtered through Celite 545® and the filtrate is concentrated in vacuo. 1H NMR analysis shows an 1:8.3 ratio of exo-(4-ethylidene-8-methoxy-3,4-dihydro-1H-pyrano[3,4-c]pyridine) to endocyclic (4-ethyl-8-methoxy-1H-pyrano[3,4-c]pyridine) product. The dark residue is chromatographed on silica gel using 5% EtOAc/hexanes to provide 4-ethyl-8-methoxy-1H-pyrano[3,4-c]pyridine, the endocyclic form, as a colorless oil. 1H-NMR (CDCl3, 400 MHz): δ1.13 (t, J=7.4 Hz, 3H, --CH3); 2.30 (q, J=7.4 Hz, 2H, --CH2 --); 3.95 (s, 3H, --OCH3); 5.04 (s, 2H, --CH2O); 6.55 (d, J=5.4 Hz, 1H, Aromatic); 8.04 (d, J=5.4 Hz, Aromatic). Anal. Calcd for C11H13NO2.0.10CHCl3.0.05C3H8O: C, 65.54; H, 6.60; N,6.79. Found: C, 65.48; H, 6.57; N, 6.89. Mass Spectrum (FAB+): m/e 192 (M+1,100%).

Aufarbeitung

  1. customis purged with a stream of nitrogen for 20 minutes
  2. temperatureat reflux for 15 hours under nitrogen
  3. temperatureheated for 2 hr
  4. temperatureThe mixture is heated
  5. temperatureto reflux for an additional 2 hr
  6. filtrationfiltered through Celite 545®
  7. concentrationthe filtrate is concentrated in vacuo
  8. customThe dark residue is chromatographed on silica gel using 5% EtOAc/hexanes

Quellen und Nachweise

ORD-Eintrag
ord-1a89a1959a974231a584a066c04391b9
Quelldatensatz
uspto-grants-1998_11
Patentnummer
US05840898

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