Insights into the diastereoselective control in the sulfa-Michael addition of thiols to nitroalkenes: stereoelectronic effect in the cyclic chelated transition state
two approximately 1,2-diaxial substituents due to stereoelectroniceffectcontrol. The stereoelectroniceffect in the cyclic chelated transition state was probed and verified by tuning the steric bulkiness of the corresponding substituents. The reaction involving 1-nitrocyclohexene provided perfect support for the proposed diastereoselective control model. The current investigation provided not only
Facile and Highly Stereoselective One-Pot Synthesis of Either (<i>E</i>)- or (<i>Z</i>)-Nitro Alkenes
作者:Stefania Fioravanti、Lucio Pellacani、Paolo A. Tardella、Maria Cecilia Vergari
DOI:10.1021/ol800224k
日期:2008.4.1
of catalytic amounts of piperidine over 4 A molecular sieves. Simply by changing reaction conditions (solvent and temperature) it is possible to control the stereochemical outcome of the reactions, obtaining pure (E)- and (Z)-nitro alkenes in high to excellent yields. The role of molecular sieves on the stereochemical control seems crucial in addition to that of piperidine, especially for the synthesis