1,8-Diazabicyclo(5.4.0)undec-7-ene → HCID 178453377, compound

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Reaction Steps

To a solution of the compound (8.35 g) obtained in Reference Example 1 in acetonitrile (100 mL), 1,8-diazabicyclo[5.4.0]undec-7-ene (4.58 mL) and lithium chloride (1.30 g) were added at room temperature. To this suspension, 1-trityl-1H-imidazole-4-carbaldehyde (6.90 g) was added, and the mixture was stirred overnight at room temperature. The solvent was distilled off under reduced pressure. To the residue, ethyl acetate and a 10% aqueous citric acid were added. This solution was separated into aqueous and organic layers. Then, the organic layer was washed with saturated sodium chloride solution, saturated aqueous sodium bicarbonate, and saturated sodium chloride solution in this order. The organic layer was dried over anhydrous sodium sulfate to obtain a mixture of tert-butyl (2E)-5-[(tert-butoxycarbonyl)amino]-2-[(1-trityl-1H-imidazol-4-yl)methylene]valerate and tert-butyl (2Z)-5-[(tert-butoxycarbonyl)amino]-2-[(1-trityl-1H-imidazol-4-yl)methylene]valerate (11.3 g). This mixture was suspended in methanol (500 mL). To this suspension, 10% palladium-carbon catalyst (hydrated, 4 g) was added, and the mixture was stirred at room temperature for 3 days under a hydrogen atmosphere. The catalyst was filtered off, and the filtrate was concentrated under reduced pressure. The residue was purified by silica gel chromatography (eluting solvent: methylene chloride/methanol=9/1) to obtain the title compound (5.60 g).

Provenance & Evidence