1,8-Diazabicyclo(5.4.0)undec-7-ene → Methyl 6-methoxybenzofuran-2-carboxylate
Reaction equation
[CH:1]([C:3]1[CH:14]=[CH:13][C:12]([O:15][CH3:16])=[CH:11][C:4]=1[O:5][CH2:6][C:7]([O:9][CH3:10])=[O:8])=O.C1CCN2C(=NCCC2)CC1>C1(C)C=CC=CC=1>[CH3:16][O:15][C:12]1[CH:13]=[CH:14][C:3]2[CH:1]=[C:6]([C:7]([O:9][CH3:10])=[O:8])[O:5][C:4]=2[CH:11]=1Participants
4
Reactant 2
Product 1
Reagents, catalysts & solvents 1
Procedure
A mixture of methyl 2-formyl-5-methoxyphenoxyacetate (27.7 g), 1,8-diazabicyclo[5.4.0]-7-undecene (40.8 g) and toluene (200 ml) was heated under refluxing conditions for 4 hours. The reaction mixture was concentrated under reduced pressure; after 6N hydrochloric acid was added, the residue was extracted with ethyl acetate. After the ethyl acetate layer was washed with water and dried (MgSO4), the solvent was distilled off; 10% hydrochloric acid-methanol (30 ml) was added to the residue, followed by heating at 70° to 80° C. for 4 hours. The reaction mixture was concentrated under reduced pressure; water was added, followed by extraction with ethyl acetate. After the ethyl acetate layer was washed with water and dried (MgSO4), the solvent was distilled off; the residue was subjected to silica gel column chromatography. From the fraction eluted with chloroform-hexane (1:2, v/v), methyl 6-methoxybenzofuran-2-carboxylate (14.3 g, 57%) was obtained, which was then recrystallized from dichloromethane-isopropyl ether to yield colorless prisms having a melting point of 97° to 98° C.