Hexamethylenetetramine → 2-oxo-2H-chromene-6-carbaldehyde
Reaction equation
[O:1]=[C:2]1[C:7](CC2C=CC=CC=2)=[C:6](C)[C:5]2[CH:16]=[CH:17][C:18](O)=[CH:19][C:4]=2[O:3]1.C1N2CN3CN(C2)CN1C3.[C:31](O)(C(F)(F)F)=[O:32]>>[CH:31]([C:19]1[CH:18]=[CH:17][CH:16]=[C:5]2[C:4]=1[O:3][C:2](=[O:1])[CH:7]=[CH:6]2)=[O:32].[CH:31]([C:17]1[CH:16]=[C:5]2[C:4](=[CH:19][CH:18]=1)[O:3][C:2](=[O:1])[CH:7]=[CH:6]2)=[O:32]Participants
5
Procedure
2-Oxo-3-benzyl-4-methyl-7-hydroxyl-2H-1-benzopyrane (512 mg, Example 1) and HMTA (140 mg) are mixed in TFA (5 mL). The reaction mixture is heated at reflux overnight. The solvent is removed under reduced pressure. The residue is purified over silica gel column (Hexanes:EtOAc, 85:15) to afford the desired 8-formyl coumarin (107 mg) and 6-formyl coumarin derivative (35 mg).