反应详情

A solution of 6-amino-4-methyl-2,10-dihydro-9-oxa-1,2,4a-triaza-phenanthren-3-one (Preparation #2, Step E; 5 g, 21.6 mmol) and 3-oxo-azetidine-1-carboxylic acid tert-butyl ester (7.37 g, 43.1 mmol) in MeOH (90 mL) and HOAc (10 mL) was stirred at rt for 2 h. Sodium cyanoborohydride (2.7 g, 43.1 mmol) was added in portions and the resulting dark solution was stirred at rt for 2 h. The solvent was removed in vacuo and the residue was washed with aqueous Na2CO3 (100 mL) and extracted with EtOAc (4×100 mL). The combined organic phase was dried over Na2SO4, filtered and concentrated in vacuo. The residue was purified by column chromatography on silica gel (eluting with 10-50% EtOAc in petroleum ether) to give 3-(4-methyl-3-oxo-2,3,4,10-tetrahydro-9-oxa-1,2,4a-triaza-phenanthren-6-ylamino)-azetidine-1-carboxylic acid tert-butyl ester (4.48 g, 54%) as a solid. 1H NMR (CDCl3, 400 MHz): δ 8.28 (brs, 1H), 6.87 (d, J=8.4 Hz, 1H), 6.15 (s, 1H), 6.13 (d, J=8.4 Hz, 1H), 4.70 (m, 1H), 4.58 (d, J=13.2 Hz, 2H), 4.30 (m, 2H), 4.17 (m, 1H), 4.01 (m, 1H), 3.75 (m, 2H), 1.51 (d, J=6.8 Hz, 3H), 1.47 (s, 9H).

1. customThe solvent was removed in vacuo
2. washthe residue was washed with aqueous Na2CO3 (100 mL)
3. extractionextracted with EtOAc (4×100 mL)
4. dry with materialThe combined organic phase was dried over Na2SO4
5. filtrationfiltered
6. concentrationconcentrated in vacuo
7. customThe residue was purified by column chromatography on silica gel (eluting with 10-50% EtOAc in petroleum ether)