1,8-Diazabicyclo(5.4.0)undec-7-ene → 1-tert-Butyl 3-ethyl 2,5-dihydro-1H-pyrrole-1,3-dicarboxylate

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Reaction Steps

To a solution of the crude 4-benzoyloxy-pyrrolidine-1,3-dicarboxylic acid 1-tert.-butylester 3-ethylester from the benzoylation described above in 75 ml dry toluene was added 4.11 g (27 mmol) DBU. The dark, heterogeneous mixture was stirred at room temperature for 16 h. After this time no starting material was detectable by TLC and GC analysis. The mixture was filtered through a short column of silica (elution with petrolether/ethyl acetate 1:1) and evaporated. Bulb-to-bulb distillation of the residual slightly yellow oil gave 4.16 g (86%) 2,5-dihydro-pyrrole-1,3-dicarboxylic acid 1-tert.-butylester 3-ethyl ester as a colorless oil b.p. 110° C./0.2 mbar, which slowly solidified to a waxy mass on standing in the freezer.

Provenance & Evidence