6-cyclopropylmethoxy-5-(3,3-difluoro-azetidin-1-yl)-pyrazine-2-carboxylic acid 、
Acetic acid 3-methyl-pyrrolidin-3-yl ester 以isolated (20 mg, 28.2%) as off white solid的产率得到acetic acid 1-[6-cyclopropylmethoxy-5-(3,3-difluoroazetidin-1-yl)pyrazine-2-carbonyl]-3-methyl-pyrrolidin-3-yl ester