corresponding 5-butyl-1-phenyl-1H-pyrazole-3-carboxylate product 5 by a ratio of at least 6:1, a complete reversal of the regioselectivity observed for 1. The structures of 4 and 5 were assigned definitively by NOE difference experiments. Regiochemical and configurational assignments of the mono- and bis(methoxyimino) derivatives of 1 were also achieved by ID and 2D 1H and 13C nmr methods.
2,4-二氧
辛酸乙酯(1)被选择性保护为2-(甲氧基亚
氨基)衍
生物2。当2与苯
肼盐酸盐反应时,3-丁基-
1-苯基-1H-吡唑-5-羧酸乙酯(4)优于相应的5-丁基-1-苯基-
1H-吡唑-3-羧酸酯产物5以至少6:1的比率完全观察到1的区域选择性。通过NOE差异实验确定了4和5的结构。的单-和二(甲氧基亚
氨基)衍
生物的区域
化学和构型的分配1也可以通过1D和2D 1 H和13 C nmr方法获得。