Hydrochloric Acid → 4-(5-Amino-3-tert-butyl-pyrazol-1-yl)-piperidine-1-carboxylic acid benzyl ester

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Reaction Steps

A yellow solution of Intermediate 16a (1.80 g, 7.22 mmol), 4,4-dimethyl-3-oxopentanenitrile (1.08 g, 8.66 mmol), and HCl (4M in dioxane, 2.70 mL, 10.8 mmol) in EtOH (25 mL) was stirred at reflux for 4 h. The cooled solution was applied to an SCX-2 cartridge (50 g), washed with MeOH (100 mL). The product was eluted with 2M NH3 in MeOH (100 mL); concentration in vacuo left a yellow oil (772 mg). FCC, using 0-5% MeOH in DCM, gave the title compound as a yellow gum (550 mg, 21%). LCMS (Method 3): Rt 2.88 min, m/z 357 [MH+].

Provenance & Evidence