[GSR]

hi,

which is the best reagent(s)/solvent(s) system for the N-methylation of haloquinoline derivatives which avoids Sn2 displacement.

regards

GSR

[laotree]

Your quinoline has an amine or methylation of the nitrogen of quinoline?

If your quinoline has an amine, try reductive amination or HCOH/HCOOH.
Borch reductive amination or alkylation. The amine (1equiv.) and ketone or aldehyde (1.5 equiv.) were dissolved into CH2Cl2 or dichloroethane. The mixture was stirred for 3 hours at 60oC. The resulting mixture was cooled to room temperature, and then acetic acid (2.5 equiv.)  and NaBH3CN or NaBH(OAc)3 (3equiv.) was added into the mixture. The resulting mixture was stirred for another 8 hours. Ethyl acetate was used to dilute the mixture, and brine was sued to wash the organic layer. The organic layer was dried and concentrated . The resulting residue was purified by silica gel column to afford 70% product. Click here to learn more. This reaction is similar to Eschweiler-Clarke reaction, in which formaldehyde is used, and formic acid is used as hydrogen donor.
Borrowed from ecompound.com

good luck!