Yield:689254-23-7 61%

Reaction Conditions:

with N-Bromosuccinimide;2,2'-azobis(isobutyronitrile) in tetrachloromethane; for 3.5 h;Heating / reflux;

Steps:

VIII

A solution of 2,3-difluoro-1-methoxy-4-nnethyl-benzene (39.5 g, 0.25 mol), N-bromo succinimide (44.5 g, 0.25 mol), and azobisisobutyronitrile (0.41 g, 2.5 mmol) in CCI₄ (300 ml.) was stirred at reflux for 3.5 h. Then the formed succinimide was removed by filtration, and the filtrate was concentrated in vacuo. The residue was dissolved in Et₂O (200 ml.) and concentrated to about 100 ml_. After cooling in an ice-bath the formed precipitate was filtered off, washed with cold Et₂O, and dried in vacuo to give the product as a white solid. Yield: 36.O g (61%) R_f 0.3 (silica gel, petrol ether/EtOAc 20:1)

References:

WO2007/14895,2007,A2 Location in patent:Page/Page column 36; 37