2-CHLORO-3-(PIPERAZINYL)PYRAZINE synthesis

Yield: 96%

Reaction Conditions:

Stage #1:2-Chloro-3-(4-tert-butoxycarbonyl-1-piperazinyl)pyrazine with hydrogenchloride in 1,4-dioxane at 20;
Stage #2: with sodium hydroxide in 1,4-dioxane;dichloromethane;water

Steps:

2
To a solution of 3'-chloro-2,3,5,6-tetrahydro-[l,2']bipyrazinyl-4-carboxylic acid t-butyl ester (10 g, 33.4 mmol, 1 eq) in 1,4-dioxane (160 mL) add a 4 M solution of hydrochloric acid in 1,4-dioxane (80 mL, 0.3 mol, 10 eq) and stir under nitrogen at room temperature overnight. Dilute with DCM (600 mL) then basify with 50% aqueous sodium hydroxide. Add water (100 mL), separate the layers and extract the aqueous twice with DCM (200 mL). Combine the organic extracts, wash with saturated aqueous sodium chloride, dry (magnesium sulfate), filter, and concentrate to give 3'-chloro- 3,4,5, 6-tetrahydro-2H-[l,2']bipyrazinyl as a viscous oil which solidifies on standing (6.39 g, 96%). MS (ES): m/z = 199.1, 201.1 [M+H]⁺.

References:

ELI LILLY AND COMPANY WO2009/29439, 2009, A1 Location in patent:Page/Page column 14