Mechanism of the Acid-Mediated Thermal Fragmentation of 5-Spirocyclobutane-isoxazolidines
作者:Franca M. Cordero、Carolina Vurchio、Alberto Brandi、Remo Gandolfi
DOI:10.1002/ejoc.201100621
日期:2011.10
Protonation at the nitrogen of 5-spirocyclopropane-isoxazolidines induces clean thermal rearrangement/fragmentation to β-lactams and ethylene. Under the same conditions, homologous 5-spirocyclobutane-isoxazolidines undergo unselective fragmentation to give cyclobutyl derivatives through a completely different mechanism. Experimental data and DFT calculations show that the process is initiated with
A visible-light-driven and room temperature photo-Wolff-Kischner reaction of sulfur ylides and N-tosylhydrazones has been developed for the first time to provide modular access to alkene synthesis. The high functional group tolerance and broad substrate scope were demonstrated by more than 60 examples. Both E- and Z-olefinic stereochemistry in the products could be controlled with excellent stereoselectivity