p-Toluenesulfonic acid → Ethyl 2-methyl-4-(2-thienyl)-5-oxo-1,4,5,7-tetrahydrofuro[3,4-b]pyridine-3-carboxylate
Reaction equation
[CH3:1][C:2]1[NH:3][C:4](CO)=[C:5]([C:18]([O:20][CH2:21]C)=[O:19])[CH:6]([C:13]2[S:14][CH:15]=[CH:16][CH:17]=2)[C:7]=1[C:8]([O:10][CH2:11][CH3:12])=[O:9].C1(C)C=CC(S(O)(=O)=O)=CC=1>C(O)C>[CH3:1][C:2]1[NH:3][C:4]2[CH2:21][O:20][C:18](=[O:19])[C:5]=2[CH:6]([C:13]2[S:14][CH:15]=[CH:16][CH:17]=2)[C:7]=1[C:8]([O:10][CH2:11][CH3:12])=[O:9]Participants
4
Reactant 2
Product 1
Reagents, catalysts & solvents 1
Procedure
A solution of diethyl 2-methyl-4-(2-thienyl)-6-hydroxymethyl-1,4-dihydropyridine-3,5-dicarboxylate (400 mg) and p-toluenesulfonic acid (catalytic amount) in 99% ethanol (10 ml) was refluxed with stirring for 2 hours. After the resultant solution was concentrated, the residue was pulverized. The powder was recrystallized from ethyl acetate to give colorless prisms (203.2 mg) of ethyl 2-methyl-4-(2-thienyl)-5-oxo-1,4,5,7-tetrahydrofuro[3,4-b]pyridine-3-carboxylate, m.p. 232° C.