کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
5272370 | 1385462 | 2009 | 4 صفحه PDF | دانلود رایگان |

An alternative to the use of expensive auxiliaries or catalysts in the synthesis of chiral 2-substituted pyrrolidines is described. Thus, commercial, cheap 4-(S)-hydroxyproline was readily transformed into optically pure pyrrolidines, using a one-pot decarboxylation-alkylation reaction as the key step. In this reaction, an acyliminium intermediate was generated, which was trapped by carbon nucleophiles. As postulated by Woerpel, the addition of the nucleophiles to the five-membered ring iminium ions took place stereoselectively, affording 2,4-cis-disubstituted pyrrolidines in high de. The hydroxy group at C-4 can then be removed, or alternatively, it can be used to create new functionalities in the molecule. In this way, optically pure alkaloid analogues and iminosugars were prepared.
In a few steps, enantiopure alkaloid analogues and iminosugars were obtained from inexpensive hydroxyproline derivatives. As postulated by Woerpel, 2,4-cis-pyrrolidines were formed in high de due to stereoelectronic effects.
Journal: Tetrahedron Letters - Volume 50, Issue 27, 8 July 2009, Pages 3974-3977