Yield:1204602-95-8 77%

Reaction Conditions:

Stage #1: 1-oxo-octahydro-pyrrolo[1,2-a]pyrazine-6-carboxylic acid ethyl esterwith lithium aluminium tetrahydride in tetrahydrofuran at 0 - 80; for 18.75 h;
Stage #2: with water;sodium hydroxide in tetrahydrofuran at 0;

Steps:

XVI.B

Step B: Preparation of 5i; To a suspension of LiAlH₄ (1.4 g, 36.9 mmol, 3.0 eq.) in THF (30 mL) at 0° C. was added dropwise a solution of compound 16 (2.6 g, 12.2 mmol, 1.0 eq.) in THF (20 mL) over 45 min. The reaction mixture was stirred at room temperature for 16 hours and then at 80° C. for 2 hours. The reaction was cooled to 0° C. and H₂O (1.6 mL), 10% NaOH (1.6 mL) and H₂O (2.0 mL) were added. The resulting mixture was filtered, the precipitate washed with dichloromethane and the filtrate was concentrated under reduced pressure to afford 51 (1.48 g, 77%) as a colorless oil.

References:

US2010/9980,2010,A1 Location in patent:Page/Page column 15-16