Dichloromethane → Acetyl chloride
Reaction equation
[C:1]([S:4][C:5]1[C:12]([F:13])=[C:11]([F:14])[C:8]([CH:9]=[O:10])=[C:7]([F:15])[C:6]=1[F:16])(=[O:3])[CH3:2].C([O-])(=S)C.C([O-])(=S)C.[K+].SC1C(F)=C(F)C(C=O)=C(F)C=1F.C(Cl)[Cl:40]>>[C:1]([Cl:40])(=[O:3])[CH3:2].[C:1]([S:4][C:5]1[C:12]([F:13])=[C:11]([F:14])[C:8]([CH:9]=[O:10])=[C:7]([F:15])[C:6]=1[F:16])(=[O:3])[CH3:2]Participants
Procedure
The next target aldehyde was 4-(S-acetylthio)-2,3,5,6-tetrafluorobenzaldehyde (9) (FIG. 35). The fluorine atom in the para position of pentafluorobenzenes is known to be very reactive toward nucleophilic substitution. Indeed, pentafluorophenyl-substituted porphyrins were recently reported to undergo fluoro-substitution by alkyl thiols (Shaw et al. (1999) Tetrahedron Lett. 40: 1595–1596; Shaw et al. (1999) Tetrahedron Lett. 40: 7585–7586). This result encouraged us to attempt a similar substitution of pentafluorobenzaldehyde with thioacetate using conditions resembling those used in the reaction of potassium thioacetate with benzyl halides. After a vigorous reaction we found that the substrate had vanished, and the only product was a very polar substance which bound at the origin of TLC (silica, CH2Cl2). We surmised that the latter molecule might be the anion of 4-mercapto-2,3,5,6-tetrafluorobenzaldehyde (formed by thioester cleavage following nucleophilic substitution), and upon treatment with acetyl chloride the desired aldehyde 9 was obtained in 69% yield after chromatography.
Workup
- customAfter a vigorous reaction we
Sources & evidence
- ORD record
- ord-0380f35684064e28998db1839b15965a
- Source dataset
- uspto-grants-2006_05
- Patent number
- US07042755B1
Reaction notes
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