(1S,2R)-2-[(2-methylpropan-2-yl)oxycarbonylamino]cyclopentane-1-carboxylic acid

Conditions: temp:0.00; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: To a mixture of (1S,2R)-2-[(tert-butoxycarbonyl)amino]cyclopentanecarboxylic acid (0.88 g) and DMF (8.0 ml) were added cesium carbonate (2.5 g) and methyl iodide (0.82 g) under ice-cooling, followed by stirring at room temperature for 1.5 hours. To the reaction mixture ethyl acetate and water under ice-cooling were added. The organic layer was separated, the aqueous layer was extracted with ethyl acetate (15 ml), and the organic layer was combined and washed with a 10% aqueous citric acid solution, a saturated sodium bicarbonate solution, water, and saturated brine in this order. The organic layer was dried over anhydrous magnesium sulfate and concentrated under reduced pressure to obtain methyl (1S,2R)-2-[(tert-butoxycarbonyl)amino]cyclopentanecarboxylate (0.85 g). cooling were added The organic layer was separated the aqueous layer was extracted with ethyl acetate (15 ml) washed with a 10% aqueous citric acid solution The organic layer was dried over anhydrous magnesium sulfate concentrated under reduced pressure