1,8-Diazabicyclo(5.4.0)undec-7-ene → 6-Bromo-2-oxo-1,2-dihydro-indole-3,3-dicarboxylic acid di-tert-butyl ester

Participants

Reaction Conditions

Reaction Steps

2-(2-Amino-4-bromo-phenyl)-malonic acid di-tert-butyl ester (10.00 g, 25.9 mmol) and diisopropylethyl amine (22.6 ml, 129.6 mmol) were dissolved in 100 ml of anhydrous dichloromethane (DCM) under an atmosphere of dry N2. The solution was cooled to 0° C. and triphosgene (2.82 g, 9.50 mmol) was added portionwise over a period of 15 minutes. After the addition was complete, the reaction mixture was warmed to ambient temperature and stirred for 1.5 hours after which time 1,8-diazabicyclo[5.4.0]undec-7-ene (19.4 ml, 129.5 mmol) was added and the mixture was stirred for an additional 1 hour. The reaction mixture was then partitioned between water and DCM. The DCM layer was then washed 3 times with 10% aqueous NaHSO4, dried over MgSO4, filtered and concentrated under vacuum to give a green foam. The green foam was stirred in hexanes overnight. The precipitate was collected and washed with hexanes, dried under vacuum to give 5.10 g of the titled compound as a white solid.

Provenance & Evidence