(±)-(exo,exo)-3-(hydroxymethylene)-5,6-(isopropylidenedioxy)bicyclo[2.2.1]heptan-2-one make the reactions between this β-diketone and hydrazines particularly interesting for elucidating the mechanism of pyrazole formation. The isolation and X-ray structure determination of two 5-hydroxy substituted Δ2-pyrazolines [(±)-(3aR*,4R*,5R*,6S*,7R*,7aR*)-7a-hydroxy-5,6-(isopropylidenedioxy)-3a,4,5,6,7,7a-hexahydro-4
(±)-(exo,exo)-3-(
羟基亚甲基)-5,6-(异丙基二烯二氧基)双环[2.2.1]庚-2--2-的结构特征使该
β-二酮与
肼之间的反应特别有趣阐明
吡唑的形成机理。分离和X射线结构测定的两个5羟基取代的Δ 2 -pyrazolines [(±) - (3A - [R *,4 - [R *,5 - [R *,6小号*,7 - [R *,7α - [R *) -图7a -羟基-5,6-(异丙基二烯二氧基)-3a,4,5,6,7,7a-六氢-4,7-
甲醇-1 H-
吲唑]和[(±)-(3a S *,4 R * ,5 R *,6 S*,7 R *,7a R *)-7a-羟基-5,6-(异亚丙基-二氧基)-1-苯基-3a,4,5,6,7,7a-六氢-4,7-甲基-1 H-
吲唑]是确定机制的决定因素。除B3LYP / 6-31G *以外,还对所有中间体二羟基
吡唑烷和5-羟基
吡唑啉进行了计算。最后,已通过实验(13