1-(2-Chloro-benzenesulfonyl)-4-cyanomethyl-piperidine-4-carboxylic acid ethyl ester → 4-(2-Amino-ethyl)-1-(2-chloro-benzenesulfonyl)-piperidine-4-carboxylic acid ethyl ester

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Reaction Steps

1-(2-Chloro-benzenesulfonyl)-4-cyanomethyl-piperidine-4-carboxylic acid ethyl ester (8.5 g) dissolved in MeOH/AcOH (1:1, 250 ml) was hydrogenated over PtO2 (2.6 g) for 4 h at atmospheric pressure until full conversion (control by thin layer chromatography). The catalyst was filtered off and the filtrate was concentrated in vacuo. The residue was dissolved in AcOEt and washed with 1M aqueous NaOH then with brine. The organic layer was dried over magnesium sulphate, the solvent removed in vacuo to give the desired product, crude light yellow oil (7.09 g), as a mixture together with some already spirocyclised amide. MS (ESI): 375.1 MH+). The crude material was directly used as such in the subsequent ring closure reaction.

Provenance & Evidence