1-ethyl-2-[(E)-2-butenoyl]-5-spirocyclopentane-pyrazolidin-3-one 、
环戊二烯 在
Lewis acid 、
S-4,5-二氢-2-(2-((S)-4,5-二氢-4-异丙基噁唑-2-基)丙-2-基)-4-异丙基噁唑 作用下,
以
二氯甲烷 为溶剂,
生成 2-[(1R,2R,3S,4S)-3-methylbicyclo[2.2.1]hept-5-ene-2-carbonyl]-1-ethyl-5-spirocyclopentyl-pyrazolidin-3-one 、 2-[(1'S,2'S,3'R,4'R)-3-methylbicyclo[2.2.1]hept-5'-en-2'-carbonyl]-1-ethyl-5-spirocyclopentyl-pyrazolidin-3-one 、