4-(2-Propyn-1-yl)morpholine → 5-(Morpholin-4-yl)pent-3-yn-2-one

Participants

Reaction Steps

To a cooled (−40° C., CH3CN/CO2) solution of 4-(2-propyn-1-yl)morpholine (2.2 g, 17.58 mmol) in THF (5 mL) was added dropwise via. syringe under N2 a solution of 2 M isopropylmagnesium chloride in THF (10 mL, 20.00 mmol). The reaction was stirred for 1 hr then a solution of N-methoxy-N-methylacetamide (2.2 mL, 20.69 mmol) in THF (5 mL) was added in one portion. The reaction was stirred for 2 hr (allowed to slowly warm to RT), quenched with aq. NH4Cl, extracted with EtOAc, washed with brine, dried (Na2SO4), filtered and evaoprated to dryness under vacuum. The remaining was purified by silica gel chromatography (Analogix, SF25-60 g, 0 to 80% EtOAc in hexanes). The pure fractions were combined and evaporated to dryness to give the product 5-(4-morpholinyl)-3-pentyn-2-one (2.09 g, 12.50 mmol, 71.1% yield) as a yellow oil. 1H NMR (400 MHz, DMSO-d6) δ 3.62-3.57 (m, 4H), 3.56 (s, 2H), 2.49-2.43 (m, 4H), 2.34 (s, 3H). MS (ES)+m/e 168.0 [M+H]+.

Provenance & Evidence