Diisopropylethylamine → 5-(1,1-Dimethylethyl) 1-ethyl 4,6-dihydro-3-[[2-(2-naphthalenyl)-1-oxopropyl]amino]pyrrolo[3,4-c]pyrazole-1,5-dicarboxylate

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Reaction Steps

To a solution of 2-naphthalen-2-yl-propionic acid (1.48 g. 7.4 mmol) in DCM (40 ml) and DMF cat., (COCl) 2 (0.83 ml, 9.65 mmol) in DCM (10 ml) was added dropwise. The mixture was stirred at r.t. for 30 min. The reaction mixture was concentrated under vacuum, reconstituted twice with toluene and concentrated. A solution of the obtained acyl-chloride in THF (40 ml) was added slowly to a mixture of 3-amino-4,6-dihydro-pyrrolo[3,4-c]pyrazole-1,5-dicarboxylic acid 5-tert-butyl ester 1-ethyl ester (2.0 g, 6.75 mmol) and DIEA (5.8 ml, 33.3 mmol) in THF (40 ml) at 0-5° C. The reaction was allowed to reach r.t. and stirred overnight. The mixture was filtered and the solution evaporated to dryness under vacuum. The resulting residue was dissolved in DCM and the obtained solution was washed with brine, dried over sodium sulfate, filtered and evaporated to dryness. The crude product was purified by flash-chromatography (eluent: ethyl acetate/cyclohexane 3/7 then 4/6) to give 3.0 g (93% yield) of the title compound as a white solid.

Provenance & Evidence