N-bromobutanimide → 3-(Bromomethyl)-5-chloro-1-benzothiophene
Reaction equation
[Cl:1][C:2]1[CH:3]=[CH:4][C:5]2[S:9][CH:8]=[C:7]([CH3:10])[C:6]=2[CH:11]=1.[Br:12]N1C(=O)CCC1=O>>[Cl:1][C:2]1[CH:3]=[CH:4][C:5]2[S:9][CH:8]=[C:7]([CH2:10][Br:12])[C:6]=2[CH:11]=1Participants
Procedure
Reaction of chloroacetone with 4-chlorothiophenol gave (4-chlorophenyl)thiomethyl methyl ketone, which was cyclized by reaction with polyphosphoric acid to 5-chloro-3-methylbenzothiophene. Bromination of the latter compound by photochemical reaction with N-bromosuccinimide provided 5-chloro-3-bromomethylbenzothiophene, which was reacted with sodium cyanide to give 5-chloro-3-cyanomethylbenzothiophene. The latter compound was hydrolyzed and esterified to give methyl α-(5-chloro-3-benzothienyl)acetate. Reaction of the ester with sodium methoxide and n-butyl nitrite afforded methyl α-hydroxyimino-α-(5-chloro-3-benzothienyl)acetate. Reduction of the oxime by reaction with zinc and formic acid and subsequent reaction with di-tert.-butyl carbonate gave N-tert.-butoxycarbonyl-(5-chloro-3-benzothienyl)glycine. NMR (CDCl3): δ 1.1-1.5 (broad s, 9H); δ 5.4-5.7 (broad s, 1H); δ 7.2-8.0 (m, 4H).
Sources & evidence
- ORD record
- ord-23e680ffe3ac461389a87141dbfa1d2d
- Source dataset
- uspto-grants-1985_01
- Patent number
- US04492693
Reaction notes
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