Avalos Martin, Babiano Reyes, Cintas Pedro, Clemente Fernando R, Gordillo Ruth, Jiménez José L, Palacios Juan C
Departamento de Química Orgánica, Facultad de Ciencias, Universidad de Extremadura, E-06071 Badajoz, Spain.
J Org Chem. 2003 Aug 8;68(16):6338-48. doi: 10.1021/jo034188r.
A series of highly funtionalized beta-lactams and thiiranes can be generated on treatment of 1,3-thiazolium-4-olates (thioisomünchnones) with aliphatic aldehydes. Although in some cases a variety of products have been obtained, the present paper now provides a mechanistic rationale to explain the product distribution based on stereoelectronic effects. Thus, ring fragmentation of the initial [3+2] cycloadduct is essentially dictated by the electronic character of the aryl substituent on the nitrogen atom of the parent thioisomünchnone. However, further evolution of such cycloadducts into beta-lactams or thiiranes is governed by steric effects to a large extent. Evidence for such interactions has been obtained by computing PM3-optimized diastereomeric transition structures in the reaction of a thioisomünchnone with a chiral aliphatic aldehyde.
用脂肪族醛处理1,3 - 噻唑 - 4 - 醇盐（硫代异缬草酮）可生成一系列高度官能化的β - 内酰胺和硫杂环丙烷。尽管在某些情况下获得了多种产物，但本文现在基于立体电子效应提供了一个机理解释来解释产物分布。因此，初始[3 + 2]环加成物的环断裂基本上由母体硫代异缬草酮氮原子上芳基取代基的电子性质决定。然而，这种环加成物进一步演变成β - 内酰胺或硫杂环丙烷在很大程度上受空间效应控制。通过计算硫代异缬草酮与手性脂肪族醛反应中PM3优化的非对映异构过渡结构，获得了这种相互作用的证据。
