Samarium Diiodide Induced Cyclizations of γ-, δ- and ε-Indolyl Ketones: Reductive Coupling, Intermolecular Trapping, and Subsequent Transformations of Indolines
prepared by simple N‐alkylation or N‐acylation of indolederivatives with the corresponding iodo alkanones, acid chlorides, or lactones. After treatment of indolyl ketones with two equivalents of SmI2, the generated stabilized carbanionic intermediates were trapped with different electrophiles leading to a variety of highly substituted indolinederivatives in good to very good yields. In general, the cyclization
synthesis of strychnine. Secondly, we account our first steps towards the development of an atom‐economical samariumdiiodide‐inducedcascade reaction using “dimeric” indolyl ketones as cyclization precursors. In this context, we discuss plausible mechanisms for the samariumdiiodide‐inducedcascade reaction as well as transformations of the obtained tetracyclic dihydroindoline derivatives.
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.
Highly Diastereoselective Samarium Diiodide Induced Ketyl Cyclisations of Indole and Pyrrole Derivatives - Scope and Limitations
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