Here we summarise our results for SmI2-induced 5-exo-trig to 8-exo-trig reductive cyclisations of suitably substituted indole and pyrrole derivatives. All precursors were easily prepared by simple N-alkylation or N-acylation of indole and pyrrole derivatives with the corresponding iodo alkanones, acid chlorides or lactones. The SmI2-induced cyclisations in most cases provided tri- and tetracyclic derivatives
Samariumdiiodide mediated cyclizations of N‐acylatedindolederivatives bearing sulfinyl imine moieties afforded polycyclic tertiary carbinamines with moderate to excellent diastereoselectivities. Lithium bromide and water turned out to be the best additives to achieve these transformations in good yields. Using enantiopure sulfinyl imines the outcome strongly depends on the reactivity of the indole
New conditions for dearomatizingsamarium‐ketyl (hetero)arene cyclizations are reported. In many examples of these samariumdiiodide‐mediated reactions, lithium bromide and water can be used as additives instead of the carcinogenic and mutagenic hexamethylphosphoramide (HMPA). The best results were obtained for the cyclizations of N‐acylatedindolederivatives delivering the expected indolines in good
Synthesis and Evaluation of Enantiopure HMPA Analogs in Samarium‐Diiodide‐Promoted Dearomatizations of N‐Acylated Indole Derivatives
作者:Chintada Nageswara Rao、Hans‐Ulrich Reissig
DOI:10.1002/ejoc.202101065
日期:2021.12.14
Among several chiral (S)-proline-based HMPAanalogs, the shown ligand strongly activates samariumdiiodide allowing the very fast and efficient conversion of an N-acylated indole into an indoline derivative. So far the achieved enantioselectivity is at best moderate.
在几种基于手性 ( S )-脯氨酸的 HMPA 类似物中,所示配体强烈激活二碘化钐,允许 N-酰化吲哚非常快速有效地转化为二氢吲哚衍生物。到目前为止,实现的对映选择性充其量是中等的。
Novel Stereoselective Syntheses of Highly Functionalized Benzannulated Pyrrolizidines and Indolizidines by Samarium Diiodide Induced Cyclizations of Indole Derivatives
作者:Steffen Gross、Hans-Ulrich Reissig
DOI:10.1021/ol0355581
日期:2003.11.1
Suitably substituted heteroaromatic compounds such as indole and pyrrole derivatives are excellent acceptor units for intramolecular couplings of samarium ketyls. They furnish highly functionalized indole derivatives with very good diastereoselectivities additionally. Intermediate samarium enolates can be trapped by electrophiles, allowing efficient tandem reactions.