Construction of fused- and spiro-oxa-[n.2.1] skeletons by a tandem epoxide rearrangement/intramolecular [3+2] cycloaddition of cyclopropanes with carbonyls
作者:Lu-Feng Wang、Zi-Fa Shi、Xiao-Ping Cao、Bao-Sheng Li、Peng An
DOI:10.1039/c4cc02641a
日期:——
A Lewis acid promoted tandem reaction of epoxide rearrangement and intramolecular [3+2] cycloaddition reaction of cyclopropanes with carbonyls formed by epoxide rearrangement in situ, which were obtained with difficulty by a general method, is reported. A wide variety of fused- and spiro-oxa-[n.2.1] skeletons could be efficiently constructed.
Asymmetric 1,4-Reductions of Hindered β-Substituted Cycloalkenones Using Catalytic SEGPHOS−Ligated CuH
作者:Bruce H. Lipshutz、Jeff M. Servesko、Tue B. Petersen、Patrick P. Papa、Andrew A. Lover
DOI:10.1021/ol0400185
日期:2004.4.1
The reagent combination of catalytic amounts of copper hydride ligated by a nonracemic SEGPHOS ligand leads in situ to an extremely reactive species capable of effecting asymmetric hydrosilylations of conjugated cyclic enones in very high ees. An unprecedented substrate-to-ligand ratio as high as 275 000:1 for this transformation has been documented.
Some novel electron transfer mediated cascade ring-opening reactions of bicyclo[4.1.0]ketones
作者:Robert A. Batey、John D. Harling、William B. Motherwell
DOI:10.1016/0040-4020(96)00635-7
日期:1996.8
The radical ring-opening reactions of cyclopropyl ketones, mediated by samarium (II) iodide and other electron transfer agents are described. This strategy allows tandemrearrangementcyclisationreactions and the trapping of the resultant samarium (III) enolates by a variety of electrophiles, for the construction of complex bicyclic systems.
作者:Branko Juršić、Mladen Ladika、Branka Bosner、Renata Kobetić、Dionis E. Sunko
DOI:10.1016/s0040-4020(01)81740-3
日期:1988.1
pyridinium iodides 6 were solvolyzed in water and in aqueous solvents, as well as under micellar conditions. All esters show in each of the solvents normal values of secondary α-deuterium isotope effects (kHkD = 1.17–1.23). Also in comparison to saturated analogues the investigated esters show a lower solvolytic reactivity. On the basis of these results it was concluded that the solvolysis proceeds via