Cyclopropenes as C3 Building Blocks: Cyclopentenols and Large Rings from 2-Aminobicyclo[2.1.0]pentane Derivatives via Ring-Enlargement Reactions The readily available methyl 3,3-dimethylcyclopropane-1-carboxylate undergoes [2+2] cycloaddition with enamines to give 2-aminobicyclo[2.1.0]pentane derivatives in moderate to good yields. These compounds are quantitatively transformed into 3-cyclopentenols by treatment with dilute mineral acids. From enamines derived from medium-ring ketones and morpholine, tricyclic adducts are formed, which eliminate morpholine under flash-thermolysis conditions at 600°C to give macrocycles containing an E double bond and an allenic system.
作为 C3 构件的环
丙烯:通过扩环反应从 2-
氨基
双环[2.1.0]戊烷衍
生物中生成
环戊烯醇和大环 易得的 3,3-二
甲基环丙烷-1-
甲酸甲酯与烯胺发生 [2+2] 环加成反应,生成 2-
氨基
双环[2.1.0]戊烷衍
生物,收率中等至良好。这些化合物经稀矿酸处理后可定量转化为 3-
环戊烯醇。从中环酮和吗啉中提取的烯胺会形成
三环加合物,在 600°C 的闪速热解条件下消除吗啉,得到含有 E 双键和异链系统的大环。