methyl 4,4-dimethylpent-2-ynoate

Conditions: temp:25.01; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: To a solution of 1-amino-3-bromo-pyridinium 2,4-dinitro-phenolate (example 41, step 1) (1.98 g, 14.16 mmol) in DMF (20 ml) were added 4,4-dimethyl-pent-2-ynoic acid methyl ester (CAS 20607-85-6) (5 g, 14.16 mmol, 1 equiv.) and K2CO3 (3.9 g, 28.3 mmol, 2 equiv.) and stirred at 25° C. while purging air. DMF was completely evaporated, the residue dissolved in ethyl acetate and washed with water (100 ml). The organic extract was dried with sodium sulfate, filtered and evaporated to dryness. The resulting crude product along with the undesired regioisomer 4-bromo-2-tert-butyl-pyrazolo[1,5-a]pyridine-3-carboxylic acid methyl ester was purified by column chromatography. The desired 6-bromo-2-tert-butyl-pyrazolo[1,5-a]pyridine-3-carboxylic acid methyl ester (1.04 g, 24% yield) was obtained as a white solid, MS: m/e=312.2 (M+H+). while purging air DMF was completely evaporated the residue dissolved in ethyl acetate washed with water (100 ml) The organic extract was dried with sodium sulfate filtered evaporated to dryness The resulting crude product along with the undesired regioisomer 4-bromo-2-tert-butyl-pyrazolo[1,5-a]pyridine-3-carboxylic acid methyl ester was purified by column chromatography

Conditions: temp:25.01; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: To a solution of 1-amino-3-bromo-pyridinium 2,4-dinitro-phenolate (example 41, step 1) (1.98 g, 14.16 mmol) in DMF (20 ml) were added 4,4-dimethyl-pent-2-ynoic acid methyl ester (CAS 20607-85-6) (5 g, 14.16 mmol, 1 equiv.) and K2CO3 (3.9 g, 28.3 mmol, 2 equiv.) and stirred at 25° C. while purging air. DMF was completely evaporated, the residue dissolved in ethyl acetate and washed with water (100 ml). The organic extract was dried with sodium sulfate, filtered and evaporated to dryness. The resulting crude product along with the undesired regioisomer 4-bromo-2-tert-butyl-pyrazolo[1,5-a]pyridine-3-carboxylic acid methyl ester was purified by column chromatography. The desired 6-bromo-2-tert-butyl-pyrazolo[1,5-a]pyridine-3-carboxylic acid methyl ester (1.04 g, 24% yield) was obtained as a white solid, MS: m/e=312.2 (M+H+). while purging air DMF was completely evaporated the residue dissolved in ethyl acetate washed with water (100 ml) The organic extract was dried with sodium sulfate filtered evaporated to dryness The resulting crude product along with the undesired regioisomer 4-bromo-2-tert-butyl-pyrazolo[1,5-a]pyridine-3-carboxylic acid methyl ester was purified by column chromatography