Pyrrolo[3,4-c]pyrazole-5(1H)-carboxylic acid, 4,6-dihydro-, 1,1-dimethylethyl ester

Uses

4,6-Dihydro-1H-pyrrolo[3,4-c]pyrazole-5-carboxylic Acid tert-Butyl Ester is an intermediate in the synthesis of Omarigliptin (O633100), a potent and selective dipeptidyl peptidase 4 (DPP-4) inhibitor to be used as treatment for type 2 diabetes.

Synthesis

Tert-butyl 3-((dimethylamino)methylene)-4-oxopyrrolidine-1-carboxylate (1 g, 4.16 mmol, 1.00 eq.) was used as a raw material and dissolved in ethanol (10 mL) with hydrazine hydrate (340 mg, 6.79 mmol, 1.63 eq.). The mixed solution was stirred and reacted at room temperature for 5 hours. Upon completion of the reaction, the solvent was removed by vacuum concentration and the crude product obtained was purified by silica gel column chromatography with ethyl acetate/petroleum ether as eluent (the ratio was gradually adjusted from 1:5 to 1:2). Finally, 250 mg (29% yield) of tert-butyl 4,6-dihydropyrrolo[3,4-c]pyrazole-5(2H)-carboxylate was obtained and the product was a yellow oil. The product was confirmed by LC/MS (Method C, ESI) analysis: retention time RT = 1.30 min, mass-to-charge ratio m/z ~ 210.0 [M + H]+.

References

[1] Patent: WO2013/127267, 2013, A1. Location in patent: Page/Page column 97; 98
[2] Bioorganic and Medicinal Chemistry Letters, 2013, vol. 23, # 19, p. 5361 - 5366
[3] Patent: EP3144310, 2017, A1