Water → 6,7-Methylenedioxy-3-nitro-4-(2-[1,3]dioxan-2-yl-phenyl)-3,4-dihydro-(2H)-chromene

HRID 1881721Notes

Reaction equation

HRID 1881721 reaction equation
Br[C:2]1[CH:7]=[CH:6][CH:5]=[CH:4][C:3]=1[CH:8]1[O:13][CH2:12][CH2:11][CH2:10][O:9]1.[Mg].[CH2:15]1[O:27][C:26]2[CH:25]=[C:24]3[C:19]([CH:20]=[C:21]([N+:28]([O-:30])=[O:29])[CH2:22][O:23]3)=[CH:18][C:17]=2[O:16]1.O>C1COCC1.BrCCBr>[CH2:15]1[O:27][C:26]2[CH:25]=[C:24]3[C:19]([CH:20]([C:2]4[CH:7]=[CH:6][CH:5]=[CH:4][C:3]=4[CH:8]4[O:13][CH2:12][CH2:11][CH2:10][O:9]4)[CH:21]([N+:28]([O-:30])=[O:29])[CH2:22][O:23]3)=[CH:18][C:17]=2[O:16]1

Participants

7

Reactant 4

HCID 962WaterHCID 5462224MagnesiumHCID 108477842-(2-Bromophenyl)-1,3-dioxaneHCID 575569416,7-Methylenedioxy-3-nitrochromene

Product 1

HCID 690722186,7-Methylenedioxy-3-nitro-4-(2-[1,3]dioxan-2-yl-phenyl)-3,4-dihydro-(2H)-chromeneYield 61.4%

Reagents, catalysts & solvents 2

HCID 78391,2-DibromoethaneCatalystHCID 8028TetrahydrofuranSolvent2×

Conditions

Temperature
80 °C

Procedure

Acetal (5a) (9.04 g, 37.22 mmol) was dissolved in 50 ml of dry THF under an inert atmosphere in a two necked flask equipped with a condenser. Magnesium (1.8 g, 74.44 mmol) and one drop of 1,2 dibromoethane were added. This mixture was stirred at 80° C. for 45 min, and cooled to room temperature. A 50 ml solution of 2.74 g of nitrochromene (3a) (12.41 mmol) in THF was cannulated into this flask. This mixture was stirred for 30 min, and water was added to quench the reaction. The mixture was extracted with CH2Cl2 (100 ml×3), the extracts washed with brine (100 ml), dried over MgSO4 filtered, and the solvent evaporated to a brown oil from which (6a) precipitated spontaneously. The precipitate was filtered, rinsed with 30 ml of EtOAc and dried to give 2.91 g (61.4% yield). The remaining liquor was purified by flash column chromatography to give an additional 550 mg (72% combined yield): mp 207° C.; 1H-NMR (CDCl3) δ 7.50 (m, 1, ArH); 7.29 (m, 2, ArH); 6.99 (m, 1, ArH); 6.47 (s, 1, ArH); 6.38 (s, 1, ArH); 5.90 (d, 2, ArOCH2); 5.70 (s, 2, OCH2O); 4.97 (s, 1, O2CHAr); 4.71 (dq, 1, Ar2CH, J=10 Hz); 4.23 (m, 2+1, CH2(CH2O)2, CHNO2); 3.98 (m, 2, CH2(CH2O)2); 2.22 (m, 1, CH2); 1.43 (d, 1, CH2); Low resolution CIMS: m/z (rel. intensity) 386 (MH+, 100). Anal. Calcd. for C20H19NO7: C, 62.33; H, 4.97; N, 3.63. Found: C, 62.18; H, 5.37; N, 3.38.

Workup

  1. customequipped with a condenser
  2. temperaturecooled to room temperature
  3. stirringThis mixture was stirred for 30 min
  4. customto quench
  5. customthe reaction
  6. extractionThe mixture was extracted with CH2Cl2 (100 ml×3)
  7. washthe extracts washed with brine (100 ml)
  8. dry with materialdried over MgSO4
  9. filtrationfiltered
  10. customthe solvent evaporated to a brown oil from which (6a)
  11. customprecipitated spontaneously
  12. filtrationThe precipitate was filtered
  13. washrinsed with 30 ml of EtOAc
  14. customdried
  15. customto give 2.91 g (61.4% yield)
  16. customThe remaining liquor was purified by flash column chromatography
  17. customto give
  18. customan additional 550 mg (72% combined yield)

Sources & evidence

ORD record
ord-929f3c37b4d142f0904438ebf989af98
Source dataset
uspto-grants-2012_11
Patent number
US08318938B2

Reaction notes

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