4-nitrobenzyl (5R)-6-[(acetyloxy)(3,4-dihydro-2H-[1,3]thiazino[3,2-a]benzimidazol-7-yl)methyl]-6-bromo-7-oxo-4-thia-1-azabicyclo[3.2.0]hept-2-ene-2-carboxylate → (5R,6Z)-6-(3,4-dihydro-2H-[1,3]thiazino[3,2-a]benzimidazol-7-ylmethylene)-7-oxo-4-thia-1-azabicyclo[3.2.0]hept-2-ene-2-carboxylic acid

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Reaction Steps

4-nitrobenzyl (5R)-6-[(acetyloxy)(3,4-dihydro-2H-[1,3]thiazino[3,2-a]benzimidazol-7-yl)methyl]-6-bromo-7-oxo-4-thia-1-azabicyclo[3.2.0]hept-2-ene-2-carboxylate (700 mg, 1.1 mmol) was suspended in 20 ml THF and 20 ml pH=6.5 aqueous phosphate buffer. The mixture was then subjected to 45 psi hydrogen for two hours. Then it was filtered through a pad of celite and concentrated in vacuo to remove most of the THF. The solution was then cooled to zero degree and basified to pH=8 with 1 N sodium hydroxide. Then it was purified via reverse phase HPLC using 1 liter of water followed by 5%-25% acetonitrile and water. Water was then removed through concentrate in vacuo and 75 mg of product (Yield 18%) was collected. MP: >250° C.; H-NMR(D2O): δ 7.08(m, 6H), 3.70(m, 2H), 4.05(m, 2H), 3.13(m, 2H), 2.22(m, 2H); MS: 372.1(M+H).

Provenance & Evidence