Yield:-

Reaction Conditions:

with thionyl chloride for 16 h;Reflux;

Steps:

25.A
Step A. Methyl (3R)-morpholine-3-carboxylateTo a solution of (R)-morpholine-3.4-dicarboxylic acid-4-tert-butyl ester (5.00 g, 21.6 mmol) in MeOH (54 mL) was added thionyl chloride (3.16 mL, 43.2 mmol) dropwise, and the resulting mixture was heated at reflux for 16 h. The solution was cooled to ambient temperature and concentrated in vacuo. The residue was made basic with saturated aqueous 10 Na?C?3 and extracted with CH2CI2 (3 x). The combined organic extracts were dried over Na2SO4, filtered, and concentrated in vacuo to yield the title compound.

References:

MERCK & CO., INC. WO2009/120652, 2009, A2 Location in patent:Page/Page column 109