Helical primary structures of 1,3-spiroannelated five-membered rings: (±)-trispiro[4.1.1.4.2.2]heptadecane and (±)-tetraspiro[4.1.1.1.4.2.2.2]heneicosane
作者:Imelda Meyer-Wilmes、Ralf Gerke、Lutz Fitjer
DOI:10.1016/j.tet.2008.12.025
日期:2009.2
A combination of three spiroannelation methods forms the basis for a synthesis of the first two helicalhydrocarbons of 1,3-spiroannelated five-memberedrings.
三种螺氧基化方法的组合构成了1,3-螺氧基化五元环的前两个螺旋碳氢化合物合成的基础。
Palladium-Catalyzed Diastereo- and Enantioselective Wagner−Meerwein Shift: Control of Absolute Stereochemistry in the C−C Bond Migration Event
作者:Barry M. Trost、Jia Xie
DOI:10.1021/ja7111299
日期:2008.5.1
Inducing absolute stereochemistry in Wagner-Meerwein shifts was examined in a ring expansion protocol. Initiated by generation of a pi-allylpalladium intermediate by hydropalladation of allenes, the ring expansion of allenylcyclobutanol substrates proceeded with excellent diastereo- and enantioselectivities. The results demonstrate that, during the C-C bond migration process, our chiral catalysts can control the stereochemistry of both the pi-allylpalladium intermediate and the corresponding migration bond. Moreover, the stereochemical outcome of the reaction can be rationalized very well with the working model of the chiral catalyst. The method provides an efficient way to synthesize highly substituted cyclopentanones with an alpha-chiral O-tertiary center which has various synthetic applications.
Syntheses of dispiro[2.1.4.1]decane and dispiro[2.0.3.3]decane
作者:John E Baldwin、Maryann E Keene、Rajesh Shukla
DOI:10.1016/s0040-4039(00)01577-x
日期:2000.12
Efficientsyntheses of the hitherto unknown hydrocarbons dispiro[2.1.4.1]decane and dispiro[2.0.3.3]decane have been realized through reaction sequences involving spiro[3.4]octan-2-one and spiro[3.4]octan-5-one as key intermediates.