反应详情

To a solution of (5S)-N,N-bis(tert-butoxycarbonyl)-5-(2,3-difluorophenyl)-6-nitro-D-norleucinate (2.30 g, 3.975 mmol) and 1,1,3,3-tetramethylguanidine (46 mg, 0.40 mmol) in acetonitrile (20 mL) was added formaldehyde (0.15 mL, 37% aqueous solution). After stirring for 60 min, more formaldehyde (0.050 mL, 37% aqueous solution) was added. After stirring for an additional 60 min the mixture was diluted with saturated aqueous NaHCO3 and extracted with CH2Cl2 (3×). The combined organics were dried over magnesium sulfate, filtered and concentrated to give a residue that was purified by silica gel chromatography (25%→75% ethyl acetate/hexanes) to give the title compound (1.44 g). MS 409.1 (M+1-2Boc).

1. stirringAfter stirring for an additional 60 min the mixture
2. extractionextracted with CH2Cl2 (3×)
3. dry with materialThe combined organics were dried over magnesium sulfate
4. filtrationfiltered
5. concentrationconcentrated
6. customto give a residue that
7. customwas purified by silica gel chromatography (25%→75% ethyl acetate/hexanes)