(3S,6S)-4-(5-(3,4-difluorophenyl)isoxazole-3-carbonyl)-3,6-diisobutylpiperazin-2-one 、
(3S,6S)-6-cyclopentyl-3-isobutylpiperazin-2-one 、
5-(4-氰基苯基)异噁唑-3-羧酸 以to give the product 137 (69.1 mg, 39.3% yield) as a pale yellow oil的产率得到4-(3-((2S,5S)-5-cyclopentyl-2-isobutyl-3-oxopiperazine-1-carbonyl)isoxazol-5-yl)benzonitrile