Tolazoline → 1,2-Dihydro-8-fluoro-4-phenylimidazo[1,2-a]quinoxaline 5-oxide

HRID 2309687Notes

Reaction equation

[CH:1]1[CH:2]=[CH:3][C:4]([CH2:7][C:8]2[NH:12][CH2:11][CH2:10][N:9]=2)=[CH:5][CH:6]=1.F[C:14]1[CH:19]=[C:18]([F:20])[CH:17]=[CH:16][C:15]=1[N+:21]([O-])=[O:22].C(=O)([O-])[O-].[K+].[K+]>C(O)(C)C>[F:20][C:18]1[CH:19]=[C:14]2[C:15]([N+:21]([O-:22])=[C:7]([C:4]3[CH:5]=[CH:6][CH:1]=[CH:2][CH:3]=3)[C:8]3[N:9]2[CH2:10][CH2:11][N:12]=3)=[CH:16][CH:17]=1

Participants

Conditions

Temperature: 50 °C

Procedure

A mixture of tolazoline (40 g, 0.25 mol), 2,4-difluoronitrobenzene (39.75 g, 0.25 mol) and potassium carbonate (17.26 g, 0.125 mol) in isopropanol (500 ml) was heated to 50° C. for a period of two days. The solvent was removed in vacuo from the mixture and the residue was dissolved in dichloromethane. The resulting solution was filtered and the solvent removed in vacuo to yield a yellow solid which was chromatographed on silica gel using 2% methanol/chloroform as the eluent to yield 1,2-dihydro-8-fluoro-4-phenylimidazo[1,2-a]quinoxaline 5-oxide (38.5 g) as an orange solid, having a m.p. 188°-193° C., (Found: C, 68.07; H 4.23; N 14.82%; C16H12FN3O requires C 68.33; H 4.27; N 14.95%) and represented by the structural formula ##STR14##

Workup

customThe solvent was removed in vacuo from the mixture
dissolutionthe residue was dissolved in dichloromethane
filtrationThe resulting solution was filtered
customthe solvent removed in vacuo
customto yield a yellow solid which
customwas chromatographed on silica gel using 2% methanol/chloroform as the eluent

Sources & evidence

ORD record: ord-657c238ee8d54bd9a75a8cb92122b09f
Source dataset: uspto-grants-1987_09
DOI: 10.6084/m9.figshare.5104873.v1
Patent number: US04696928

Reaction notes

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