5-METHYL-2-PYRIDYLZINC BROMIDE synthesis

Yield:623577-56-0 41%

Reaction Conditions:

Stage #1: 1-methyl-3-bromo-pyrazol-5-yl nonaflate;tetrakis(triphenylphosphine) palladium⁽⁰⁾ in N,N-dimethyl-formamide at 60; for 0.166667 h;
Stage #2: (5-methylpyridin-2-yl)zinc(II) bromide in tetrahydrofuran;N,N-dimethyl-formamide at 60; for 18 h;
Stage #3: with water in tetrahydrofuran;N,N-dimethyl-formamide;

Steps:

69.3

A solution of 1-methyl-3-bromo-5- (nonafluorobutanesulfonyloxy) pyrazole from Step 2 (0.36 g, 0.784 mmol) and tetrakis (triphenylphosphine) palladium (0) (0.09 g, 10 mol%) in dry NN-dimethylformamide (2 mL) was stirred under nitrogen at 60°C for 10 min, followed by addition of a solution of 5-methylpyridin-2-ylzinc bromide in tetrahydrofuran (0.5M, 1.8 mL, 0.9 mmol). The solution was stirred at 60°C for 18 hours then cooled, diluted with water (30 mL), and extracted with ethyl acetate (2 x 20 mL). The extracts were dried (Na2SO4) and concentrated. Flash column chromatography on silica, eluting with 10% ethyl acetate-isohexane, gave 1-methyl-3-bromo-5- (5-methylpyridin-2-yl) pyrazole (0.081 g, 41%) as a yellow solid. MS (ES+) 252,254 (tMH] +).

References:

WO2003/93252,2003,A1 Location in patent:Page/Page column 101-102