D-Valine, (2S)-2-cyclohexyl-N-(2-pyrazinylcarbonyl)glycyl-3-Methyl- synthesis

Yield:1033882-31-3 99%

Reaction Conditions:

Stage #1: (R)-methyl 2-((S)-2-cyclohexyl-2-(pyrazine-2-carboxamido)acetamido)-3,3-dimethylbutanoatewith water;lithium hydroxide in tetrahydrofuran;methanol; for 3 h;
Stage #2: with phosphoric acid in tetrahydrofuran;methanol;water;ethyl acetate;

Steps:

36.B

The product from Part A (58 mg, 0.15 mmol) in a solvent mixture of THF/water/methanol (2:2:0.7 ml) was treated with LiOH (32 mg, 0.75 mmol) and stirred for 3 hours. The mixture was diluted with 50 mL EtOAc and acidified with 10% H₃PO₄. The EtOAc layer was washed with brine, dried (Na₂SO₄), and concentrated to a clear glass (60 mg, 99%). MS (ESI+) m/z=377 (M+H)⁺

References:

US2010/29686,2010,A1 Location in patent:Page/Page column 55