Hydrochloric Acid → 6-(2,3-Di-p-tolyl-5,6,7,8-tetrahydropyrido[2,3-b]pyrazin-6-yl)hexanoic acid

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Reaction Steps

Tert-butyl 6-(6-ethoxy-6-oxohexyl)-2,3-di-p-tolyl-7,8-dihydropyrido[2,3-b]pyrazine-5(6H)-carboxylate (step 4) (83 mg, 0.149 mmol) in EtOH (2 ml) was treated with 2M NaOH (0.223 ml, 0.446 mmol) and stirred at RT for 16 hours. MeOH (1 ml) and 2M HCl (0.372 ml, 0.744 mmol) were added and stirring continued at RT for 16 hours. The solvent was removed under reduced pressure and the residue was dissolved in water (30 ml). The mixture was extracted with DCM (×3) and the combined organic extracts were concentrated under reduced pressure. The crude product was dissolved in EtOH (1 ml) and treated with 2M NaOH (0.223 ml, 0.446 mmol). After stirring at RT overnight, the mixture was diluted with water (30 ml) and the pH was adjusted to pH1 using 1 M HCl. The aqueous portion was extracted with DCM (×3) and the combined organic extracts were concentrated under reduced pressure to afford an enantiomeric mixture.

Provenance & Evidence