A route for the preparation of sparteine-like diamines starting from naturally occurring amino acids has been explored. Starting from the amino acids (S)-proline and (S)-phenylalanine, two novel sparteine-like diamines 2 and 3 have been prepared. The synthetic route involves Dieckmann condensation followed by a double Mannich reaction to set up the tricyclic structure with control of the relative stereochemistry. During the Dieckmann and Mannich reactions it was found that racemisation occurred either via retro-Michael or retro-Mannich processes. Conditions for preventing racemisation in the Dieckmann reaction were uncovered but it was not possible to prevent racemisation during the double Mannich reaction. Thus, the two novel sparteine-like diamines 2 and 3 have been prepared in racemic form.
研究了一种从天然
氨基酸制备类似斯巴丁二胺的路线。以
氨基酸(S)-脯
氨酸和(S)-苯丙
氨酸为起始物,合成了两种新型斯巴丁类似二胺2和3。合成路线涉及Dieckmann缩合,随后进行双Mannich反应,以建立
三环结构并控制相对立体
化学。在Dieckmann和Mannich反应过程中发现,消旋化通过逆Michael或逆Mannich过程发生。揭示了防止Dieckmann反应中消旋化的条件,但在双Mannich反应中无法防止消旋化。因此,这两种新型斯巴丁类似二胺2和3以消旋形式合成。