1-Bromo-3-chloropropane → 2-(5-Bromo-pyridin-2-yl)-5-chloro-pentanoic acid methyl ester
Reaction equation
[CH3:1][O:2][C:3](=[O:12])[CH2:4][C:5]1[CH:10]=[CH:9][C:8]([Br:11])=[CH:7][N:6]=1.Br[CH2:14][CH2:15][CH2:16][Cl:17]>>[CH3:1][O:2][C:3](=[O:12])[CH:4]([C:5]1[CH:10]=[CH:9][C:8]([Br:11])=[CH:7][N:6]=1)[CH2:14][CH2:15][CH2:16][Cl:17]Participants
Procedure
Key building block 2-(5-bromo-pyridin-2-yl)-5-chloro-pentanoic acid (XII) can be prepared according to Scheme 8. Starting with commercially available 5-bromo-2-iodo-pyridine (XXXV), copper-catalyzed reaction with malonic acid diethyl ester furnishes 2-(5-bromo-pyridin-2-yl)-malonic acid diethyl ester (XXXVI). Hydrolysis and decarboxylation under basic conditions gives (5-bromo-pyridin-2-yl)-acetic acid (XXXVII), which subsequently can undergo nucleophilic acyl substitution with thionyl chloride in methanol to provide (5-bromo-pyridin-2-yl)-acetic acid methyl ester (XXXVIII). Deprotonation of XXXVIII with strong base followed by alkylation with 1-bromo-3-chloropropane gives 2-(5-bromo-pyridin-2-yl)-5-chloro-pentanoic acid methyl ester (XXXIX), which can then be hydrolyzed under aqueous basic conditions to furnish key building block 2-(5-bromo-pyridin-2-yl)-5-chloro-pentanoic acid (XII).
Sources & evidence
- ORD record
- ord-5acb87fed3524c039049c4b5bb073a37
- Source dataset
- uspto-grants-2012_06
- Patent number
- US08202866B2
Reaction notes
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