2-Bromo-1-ethylpyridinium tetrafluoroborate

Conditions: temp:20.01; pressure:0.00; stir:

Conditions: temp:25.01; pressure:0.00; stir:

Conditions: temp:25.01; pressure:0.00; stir:

Conditions: temp:25.01; pressure:0.00; stir:

Conditions: temp:25.01; pressure:0.00; stir:

Conditions: temp:25.01; pressure:0.00; stir:

Conditions: temp:25.01; pressure:0.00; stir:

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

Procedure: To a solution of [6-chloro-4-(4-fluoro-2-methoxy-phenyl)-pyridazin-3-yl]-methyl-amine (95 mg, 355 μmol) in dichloromethane (5 mL) was added 3-methanesulfonyl-5-trifluoromethyl-benzoic acid (95.2 mg, 355 mmol) and 2-bromo-1-ethylpyridinium tetrafluoroborate (117 mg, 426 μmol, CAS RN 878-23-9) and N-ethyldiisopropyl-amine (91.7 mg, 124 μL, 710 μmol). The reaction mixture was stirred at room temperature for 72 hours and then poured on 30 mL 10% aqueous bicarbonate solution and 30 mL dichloromethane and the layers were separated. The aqueous layer was extracted a second time with 30 mL dichloromethane. The organic layers were washed with 30 mL brine, dried over magnesium sulfate, filtered and concentrated under vacuum. The compound was purified by silica gel chromatography on a 20 g column using a MPLC system (CombiFlash Companion, Isco Inc.) eluting with a gradient of n-heptane:ethyl acetate (100:0 to 0:100). Colorless solid (63 mg, 34.3%). MS (ESI+): m/z=518.056 ([M+H]+). the layers were separated The aqueous layer was extracted a second time with 30 mL dichloromethane The organic layers were washed with 30 mL brine dried over magnesium sulfate filtered concentrated under vacuum The compound was purified by silica gel chromatography on a 20 g column eluting with a gradient of n-heptane:ethyl acetate (100:0 to 0:100)

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

Procedure: To a cold solution of 3,3-dimethyl-6-((methylamino)methyl)benzo[c][1,2]-oxaborol-1(3H)-ol (246 mg, 1.2 mmol), 4-(5-(3,5-dichlorophenyl)-5-(trifluoromethyl)-4,5-dihydroisoxazol-3-yl)-2-methylbenzoic acid (502 mg, 1.2 mmol) and 2-bromo-1-ethylpyridinium tetrafluoroborate (BEP) (292 mg, 1.32 mmol) in DCM (10 mL) was added DIPEA (464 mg, 3.6 mmol). The reaction mixture was stirred at rt overnight. Water (20 mL) was added and the mixture was extracted three times with ethyl acetate. The combined organic layers were washed with brine, dried over Na2SO4, filtered and concentrated under reduced pressure. The residue was purified by prep-HPLC to give 4-(5-(3,5-dichlorophenyl)-5-(trifluoromethyl)-4,5-dihydroisoxazol-3-yl)-N-((1-hydroxy-3,3-dimethyl-1,3-dihydrobenzo[c][1,2]oxaborol-6-yl)methyl)-N,2-di-ethylbenzamide (84 mg; yield 11.6%) as a white solid. HPLC purity: 98.30% at 220 nm and 98.87% at 254 nm; MS: m/z=604.9 (M+1, ESI+). the mixture was extracted three times with ethyl acetate The combined organic layers were washed with brine dried over Na2SO4 filtered concentrated under reduced pressure The residue was purified by prep-HPLC

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

Procedure: To a cold solution of 3,3-dimethyl-6-((methylamino)methyl)benzo[c][1,2]-oxaborol-1(3H)-ol (246 mg, 1.2 mmol), 4-(5-(3,5-dichlorophenyl)-5-(trifluoromethyl)-4,5-dihydroisoxazol-3-yl)-2-methylbenzoic acid (502 mg, 1.2 mmol) and 2-bromo-1-ethylpyridinium tetrafluoroborate (BEP) (292 mg, 1.32 mmol) in DCM (10 mL) was added DIPEA (464 mg, 3.6 mmol). The reaction mixture was stirred at rt overnight. Water (20 mL) was added and the mixture was extracted three times with ethyl acetate. The combined organic layers were washed with brine, dried over Na2SO4, filtered and concentrated under reduced pressure. The residue was purified by prep-HPLC to give 4-(5-(3,5-dichlorophenyl)-5-(trifluoromethyl)-4,5-dihydroisoxazol-3-yl)-N-((1-hydroxy-3,3-dimethyl-1,3-dihydrobenzo[c][1,2]oxaborol-6-yl)methyl)-N,2-di-ethylbenzamide (84 mg; yield 11.6%) as a white solid. HPLC purity: 98.30% at 220 nm and 98.87% at 254 nm; MS: m/z=604.9 (M+1, ESI+). the mixture was extracted three times with ethyl acetate The combined organic layers were washed with brine dried over Na2SO4 filtered concentrated under reduced pressure The residue was purified by prep-HPLC

Conditions: temp:-10.01; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: 10.65 g (41.058 mmol) of tert-butyl (3R,4S,5S)-3-methoxy-5-methyl-4-(methylamino)heptanoate (starting compound 2b) were taken up in 250 ml of dichloromethane and the solution was cooled to −10° C. Then, while stirring, 10.317 g (41.058 mmol) of N-[(benzyloxy)carbonyl]-L-valine, 16.866 g (61.586 mmol) of 2-bromo-1-ethylpyridinium tetrafluoroborate (BEP) and 28.6 ml of N,N-diisopropylethylamine were added, and the mixture was subsequently stirred at RT for 20 h. The reaction mixture was then diluted with dichloromethane and shaken twice with saturated sodium chloride solution, dried over sodium sulphate, filtered and concentrated. The residue was purified by flash chromatography on silica gel with 4:1 petroleum ether/ethyl acetate as the eluent. The corresponding fractions were concentrated and the residue was dried under high vacuum overnight. 10.22 g (51% of theory) of the title compound were obtained as a yellowish oil. the mixture was subsequently stirred at RT for 20 h dried over sodium sulphate filtered concentrated The residue was purified by flash chromatography on silica gel with 4:1 petroleum ether/ethyl acetate as the eluent The corresponding fractions were concentrated the residue was dried under high vacuum overnight

Conditions: temp:-10.01; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: 10.65 g (41.058 mmol) of tert-butyl (3R,4S,5S)-3-methoxy-5-methyl-4-(methylamino)heptanoate (starting compound 2b) were taken up in 250 ml of dichloromethane and the solution was cooled to −10° C. Then, while stirring, 10.317 g (41.058 mmol) of N-[(benzyloxy)carbonyl]-L-valine, 16.866 g (61.586 mmol) of 2-bromo-1-ethylpyridinium tetrafluoroborate (BEP) and 28.6 ml of N,N-diisopropylethylamine were added, and the mixture was subsequently stirred at RT for 20 h. The reaction mixture was then diluted with dichloromethane and shaken twice with saturated sodium chloride solution, dried over sodium sulphate, filtered and concentrated. The residue was purified by flash chromatography on silica gel with 4:1 petroleum ether/ethyl acetate as the eluent. The corresponding fractions were concentrated and the residue was dried under high vacuum overnight. 10.22 g (51% of theory) of the title compound were obtained as a yellowish oil. the mixture was subsequently stirred at RT for 20 h dried over sodium sulphate filtered concentrated The residue was purified by flash chromatography on silica gel with 4:1 petroleum ether/ethyl acetate as the eluent The corresponding fractions were concentrated the residue was dried under high vacuum overnight