Cyanoacetic acid → trans-3-(4-oxo-4H-1-benzopyran-3-yl)-acrylonitrile
Reaction equation
[O:1]=[C:2]1[C:7]2[CH:8]=[CH:9][CH:10]=[CH:11][C:6]=2[O:5][CH:4]=[C:3]1[CH:12]=O.[C:14]([CH2:16]C(O)=O)#[N:15]>N1C=CC=CC=1>[O:1]=[C:2]1[C:7]2[CH:8]=[CH:9][CH:10]=[CH:11][C:6]=2[O:5][CH:4]=[C:3]1/[CH:12]=[CH:16]/[C:14]#[N:15]Participants
4
Reactant 2
Product 1
Reagents, catalysts & solvents 1
Conditions
- Temperature
- 110 °C
Procedure
A mixture of 10.44 parts of 4-oxo-4H-1-benzopyran-3- carboxaldehyde and 5.4 parts of cyanoacetic acid are heated in an oil bath at 110° C., and to the mixture 25 volume parts of pyridine are added dropwise over about 30 seconds, after which time the whole mixture is further heated for 8 minutes. After cooling, the separated crystals are recovered by filtration, treated with activated carbon and recrystallized three times from ethanol. This procedure yields trans-3-(4-oxo-4H-1-benzopyran-3-yl)-acrylonitrile as pale-yellowish prisms. Melting point: 192°-194° C.