4-(3-Benzyloxycarbonyl-3-diazo-2-oxopropyl)-azetidin-2-one → Benzyl 3,7-dioxo-1-azabicyclo[3.2.0]heptane-2-carboxylate

HRID 1105864Notes

Reaction equation

[CH2:1]([O:8][C:9]([C:11](=[N+]=[N-])[C:12](=[O:19])[CH2:13][CH:14]1[NH:17][C:16](=[O:18])[CH2:15]1)=[O:10])[C:2]1[CH:7]=[CH:6][CH:5]=[CH:4][CH:3]=1>C([O-])(=O)C.[Rh+2].C([O-])(=O)C.C1C=CC=CC=1>[N:17]12[C:16](=[O:18])[CH2:15][CH:14]1[CH2:13][C:12](=[O:19])[CH:11]2[C:9]([O:8][CH2:1][C:2]1[CH:7]=[CH:6][CH:5]=[CH:4][CH:3]=1)=[O:10]

Participants

Conditions

Temperature: 80 °C

Procedure

A mixture of 4-(3-benzyloxycarbonyl-3-diazo-2-oxopropyl)-azetidin-2-one (718 mg. 2.5 mMol), rhodium (II) acetate (5 mg) and anhydrous benzene (50 ml) is deoxygenated by bubbling nitrogen through it for 45 minutes. The mixture is then stirred and heated in an oil bath maintained at 80° C. for 70 minutes. After cooling to room temperature, the mixture is filtered and the filtrate is evaporated under vacuum to an oil. Crystallization from ethyl acetate (5 ml)-diethylether (20 ml) provides benzyl 1-azabicyclo[3.2.0]heptan-3,7-dione-2-carboxylate (502 mg, 77% yield) as small, white prisms: mp 100°-102°; IR (CH2Cl2) 1770; 1741 cm-1 ; UV (dioxane) 220 nm; NMR (CDCl3, 300 MHz) α2.43 (dd,1,J=8 and 19, H4a), 2.94 (dd,1,J=6.5 and 19, H4b), 2.99 (dd, 1,J=2 and 16, H6B), 3.63 (dd,1,J=5 and 16, H6α), 4.18 (m,1,H5), 4.76 (S,1,H2), 5.23 (S,2,CH2 φ), and 7.40 (S,5,ArH); MS m/e 259 (M+), 231 (M+-28), 217 (M+-42), 203, 187, 186, 168 (M+-91), 124, and 91.

Workup

customis deoxygenated
customby bubbling nitrogen through it for 45 minutes
temperatureheated in an oil bath
temperatureAfter cooling to room temperature
filtrationthe mixture is filtered
customthe filtrate is evaporated under vacuum to an oil
customCrystallization from ethyl acetate (5 ml)-diethylether (20 ml)

Sources & evidence

ORD record: ord-9e0a878d824745c09ae3d48da5d0e019
Source dataset: uspto-grants-1982_01
DOI: 10.6084/m9.figshare.5104873.v1
Patent number: US04310538

Reaction notes

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