Reaction of methyl trimethylsiloxycyclopropanecarboxylates 3 with amino acids, tert-butylisonitrile and methanol furnished amino diacid derivatives 2 as the result of an Ugi 5-center 4-component reaction. This one-pot reaction involves β-formyl esters such as 1 as intermediate, which are liberated in situ. Adducts 2 could be thermally cyclized to provide γ-lactams 4 in good yields. The multi component reaction was combined with this cyclization process to a fairly efficient one-pot procedure. Thus, cyclopropane derivative 3a was converted into γ-lactam 4a in good yield. Two of the γ-lactams 4 were reduced with lithium aluminum hydride to give pyrrolidine derivatives 5. Based on an X-ray analysis of the major diastereomer of compound 5d, the diastereoselectivity of the 4-component reaction is discussed.
三甲基
硅氧烷环丙烷羧酸甲酯 3 与
氨基酸、
叔丁基异腈和
甲醇反应生成
氨基二酸衍
生物 2,这是 Ugi 5-中心 4-组分反应的结果。这种单锅反应以δ-甲酰基酯(如 1)为中间体,并在原位释放。加合物 2 可通过热环化反应生成δ-内酰胺 4,产率很高。多组分反应与这种环化过程相结合,形成了一种相当有效的单锅程序。因此,
环丙烷衍
生物 3a 以良好的收率转化为 δ³ 内酰胺 4a。用
氢化铝锂还原其中两个δ-内酰胺 4,得到
吡咯烷衍
生物 5。根据对化合物 5d 主要非对映异构体的 X 射线分析,讨论了 4 组分反应的非对映选择性。