申请人:Frontier Scientific, Inc.
公开号:US07087755B1
公开(公告)日:2006-08-08
A class of 2,4-; 2,3,4-; 2,4,6-; 2,3,4,5,6-substituted pyridines is provided which include novel compounds. The substitutions are achieved according to methods disclosed herein in which a metallated pyridine is reacted with an electrophile. Suitable electrophiles include CO2, SO2, dialkylcarbonates, ureas, formamides, amides, carboxylic acid esters, mono- and dihaloalkyls, halogens such as chlorine, fluorine, bromine, and iodine, metallic salts, sulfones, sulfonyls, aldehydes, ketones, anhydrides, nitrites, and electrophilic boron compounds including, but not limited to, boron trialkoxides and boron trihalides. The subject invention more specifically discloses a process for the synthesis of 2,6-difluoropyridin-4-ylboronic acid which comprises: (1) reacting 2,4,6-trifluoropyridine with hydrazine monohydrate to produce 2,6-difluoro-4-hydrazinopyridine, (2) reacting the 2,6-difluoro-4-hydrazinopyridine with elemental bromine to produce 4-bromo-2,6-difluoropyridine, and (3) reacting the 4-bromo-2,6-difluoropyridine with an organolithium compound and a borate at a temperature of less than about 0° C. to produce the 2,6-difluoropyridin-4-ylboronic acid, wherein said process is conducted in an organic solvent.
提供了一类包括新颖化合物的2,4-;2,3,4-;2,4,6-;2,3,4,5,6-取代吡啶。这些取代是通过本文披露的方法实现的,其中金属化的吡啶与亲电试剂发生反应。适当的亲电试剂包括CO2、SO2、二烷基碳酸酯、脲、甲酰胺、酰胺、羧酸酯、单烷基和二卤代烷基、氯、氟、溴和碘等卤素、金属盐、磺酮、磺酰基、醛、酮、酸酐、亚硝酸盐和亲电硼化合物,包括但不限于硼三烷氧化物和硼三卤化物。该发明更具体地披露了一种合成2,6-二氟吡啶-4-基硼酸的方法,包括:(1)将2,4,6-三氟吡啶与单水合肼反应,生成2,6-二氟-4-肼基吡啶,(2)将2,6-二氟-4-肼基吡啶与元素溴反应,生成4-溴-2,6-二氟吡啶,(3)将4-溴-2,6-二氟吡啶与有机锂化合物和硼酸盐在约0°C以下的温度下反应,生成2,6-二氟吡啶-4-基硼酸,其中所述过程在有机溶剂中进行。