1-Butyl-1H-pyrazole

3.102 g (18 mmol) of hydrobromic acid was gradually added dropwise to 1.86 g (15 mmol) of 3.40 g (0.05 mol) of pyrazole and 2.8 g (0.05 mol) of powdered KOH were placed in a 100 mL three-necked flask, Add 10mL DMSO as a solvent, The mixture was stirred at 80 C for 30 min, Then 7.65 g (0.05 mol) of 4-bromobutanol were added (at intervals of 30 min, Added into the flask three times), continue stirring for 20 ~ 30h, Cooled to room temperature, filtered, 20 mL of chloroform was added and the solution was washed with water (5 x 20 mL)Rotary drying gave a pale yellow liquid General procedure: Step ATo a solution of 1 eq. of the appropriate N-alkyl pyrazole in dry THF (1.5 mL/mmol), 1.1 eq. BuLi was added dropwise at -78 C. The mixture was stirred for 30 minutes and then allowed to warm up to 0 C where it was stirred for 30 minutes, then cooled back to-78 C again. 1.1 eq. DMF was added dropwise, then the reaction mixture was allowed to reach r.t. and it was stirred overnight. The mixture was quenched with cc. NH4C1 solution. The phases were separated and the aqueous layer was extracted with EtOAc. Thecombined organic layers were dried over Na2SO4, filtered and the filtrate was concentrated under reduced pressure. The residue was used in the next step without further purification. Step BTo a solution of 1 eq. of the appropriate crude aldehyde in EtOH (0.5 mL/mmol), 1.3 eq. sodium borohydride was added portionwise at -15 C and the reaction mixture was stirred at r.t. until no further conversion was observed. The mixture was poured onto crushed ice and stirred for 16 hours. The precipitate was filtered off, and the filtrate was concentratedunder reduced pressure. The oily phase was separated, and the aqueous layer was extracted with EtOAc. The combined organic layers were dried over Na2SO4, filtered and the filtrate was concentrated under reduced pressure. The product was further purified by flash chromatography if necessary. :_Using General Procedure Vb and 1 -butylpyrazole as the appropriate alkyl pyrazole, Preparation C2 was obtained.1H NMR (400 MHz, DMSO-d6) oe: 7.30 (d, 1H), 6.12 (d, 1H), 5.23 (t, 1H), 4.49 (d, 2H), 4.06 (t, 2H), 1.72 (m, 2H), 1.26 (m, 2H), 0.88 (t, 3H)

Molecular Weight:124.18
XLogP3:0.8
Hydrogen Bond Acceptor Count:1
Rotatable Bond Count:3
Exact Mass:124.100048391
Monoisotopic Mass:124.100048391
Topological Polar Surface Area:17.8
Heavy Atom Count:9
Complexity:73.3
Covalently-Bonded Unit Count:1
Compound Is Canonicalized:Yes