Diisopropylethylamine → 4-([1,4]oxazepane-4-carbonyl)-1H-pyrrole-2-carboxylic acid ethyl ester

Participants

Reaction Steps

To 1H-pyrrole-2,4-dicarboxylic acid 2-methyl ester (291 mg) in DCM (18 mL) was added [1,4]oxazepane hydrochloride (236 mg), PyBroP (802 mg) and DIEA (878 μL). The mixture was stirred for 3 h at RT after which it was washed with saturated aqueous NaHCO3 solution and 1 N HCl. The organic phase was dried (MgSO4) and concentrated in vacuo. The residue was purified by flash column chromatography on silica (ethyl acetate) to provide 4-([1,4]oxazepane-4-carbonyl)-1H-pyrrole-2-carboxylic acid ethyl ester (533 mg). This material was used directly used in the next step although traces of phosphine oxide impurities resulting from the coupling reagent were still present.

Provenance & Evidence