ethyl 2-(5-bromopyridin-2-yl)acetate synthesis

Yield: 70%

Reaction Conditions:

Stage #1:2-iodo-5-bromopyridine;diethyl malonate with 2-Picolinic acid;copper(l) iodide;caesium carbonate in 1,4-dioxane at 80; for 5 h;Inert atmosphere;
Stage #2: with lithium chloride in water;dimethyl sulfoxide at 150;

Steps:

Intermediate 118A, Preparation of ethyl 2-(5-bromopyridin-2-yl)acetate
5-bromo-2-iodopyridine (20 g, 70.4 mmoi) was dissolved in dioxane (90 mL), Diethvimalonate (13.54 g. 85 mmoi). CS2COS (34.4 g, 106 rnrnoi), and picolinic acid (1.74 g,1409 mmoi) were then added. The suspension was degassed thoroughly by 3 evacuation and nitrogen-back-fill cycles. Next, Cul (134 g, 7.04 mmoi) was added and the reaction was stirred at 80 °C under nitrogen atmosphere for 5 hours. The reaction was then cooled to rt and diluted with 50() mL water and extracted with 100 rnL EtOAc x 4. The organiclayers were concentrated and the residue was dissolved in DMSO (250 mL) and LiCI (2.99 g. 70.4 mmoi) in 10 mL water was added. The reaction was heated to 150 °C for 3 hours (observation of gas evolution), adding LiC1 (250 mg) in I mL water every 30 minutes until double decarboxylation was observed in LCMS. The reaction was cooled to rt and diluted with 500 mL water and extracted with EtOAc 2 x 200 mL. The combinedorganic layers were concentrated and the residue was purified by silica gel chromatography, eluting with a linear gradient of 0% to 100% EtOAc. Ethyl 2-(5-bromopyridin-2-vI)acetate (12 g, 49.2 mmol. 70 % yield) was isolated as a yellow oil. MS (ES) mi±: 245.9 (M+H)

References:

BRISTOL-MYERS SQUIBB COMPANY;SMITH II, Leon M.;LADZIATA, Vladimir;DELUCCA, Indawati;PINTO, Donald, J., P.;ORWAT, Michael J.;DILGER, Andrew K.;PABBISETTY, Kumar Balashanmuga;YANG, Wu;SHAW, Scott A.;GLUNZ, Peter W.;PANDA, Manoranjan WO2017/123860, 2017, A1 Location in patent:Page/Page column 254