Methyl chloroformate → (2S,3R)-3-methoxy-2-(methoxycarbonylamino)butanoic acid

A solution of O-methyl-L-threonine (1.01 g, 7.59 mmol) in saturated bicarbonate solution (93 mL) was treated dropwise with methyl chloroformate (900 μL, 1.10 g, 11.61 mmol), followed by stirring at RT for 24 h. The mixture was extracted methyl t-butyl ether and cooled to 0° C. The mixture was adjusted to pH 1-2 by addition of concentrated hydrochloric acid solution. The mixture was extracted with ethyl acetate (3×) and the combined extracts were extracted with saturated sodium chloride solution and dried (Na2SO4). The solution was concentrated in vacuo to afford the title compound (1.31 g, 90%) as a white solid. 1H NMR (400 MHz, CDCl3) δ 5.44 (d, J=8.7 Hz, 1 H), 4.39 (dd, J=8.7, 2.3 Hz, 1 H), 4.00 (dd, J=6.2, 2.4 Hz, 1 H), 3.71 (s, 3 H), 3.36 (s, 3 H), 1.21 (t, J=7.2 Hz, 3 H). MS (+ESI) m/z (rel abundance) 192 (60, M+H), 209 (100, M+NH4).

1. extractionThe mixture was extracted methyl t-butyl ether
2. temperaturecooled to 0° C
3. additionThe mixture was adjusted to pH 1-2 by addition of concentrated hydrochloric acid solution
4. extractionThe mixture was extracted with ethyl acetate (3×)
5. extractionthe combined extracts were extracted with saturated sodium chloride solution
6. dry with materialdried (Na2SO4)
7. concentrationThe solution was concentrated in vacuo

ORD record

ord-ee3335b65500408fac05f993e15825bb

Source dataset

uspto-grants-2014_04

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US08691938B2