Ruthenium-Catalyzed [2 + 2] Cycloadditions of 2-Substituted Norbornenes
作者:Robert W. Jordan、William Tam
DOI:10.1021/ol006397t
日期:2000.9.1
stereoelectronic effects. The effect of remote substituents on ruthenium-catalyzed [2 + 2] cycloadditions of 2-substituted norbornenes has been investigated. The cycloadditions occurred at room temperature in excellent yields, and regioselectivities of 1.2:1 to 7.5:1 were observed with various 2-substituted norbornenes.
1,3-Dipolar cycloaddition of nitrile oxides with unsymmetrically substituted norbornenes
作者:Peter Mayo、Tiffany Hecnar、William Tam
DOI:10.1016/s0040-4020(01)00573-7
日期:2001.7
1,3-Dipolar cycloadditions of nitrileoxides with unsymmetrically substituted norbornenes were investigated. The cycloadditions were found to be completely stereoselective, giving only the exo cycloadducts in moderate to good yields. Regioselectivities in the cycloadditions ranging from 50:50 to 100:0 were observed with various unsymmetrically substituted norbornenes.
Remote substituent effects on regioselectivity in the Pauson–Khand reaction of 2-substituted norbornenes
作者:Peter Mayo、William Tam
DOI:10.1016/s0040-4020(01)00574-9
日期:2001.7
of a remote substituent on the regioselectivity in the Pauson–Khand reaction of 2-substituted norbornenes has been investigated. Moderate level of regioselectivity was observed and the regioselectivity increases as the electron-withdrawing power of the remote substituent increases. exo Substituents at C-2 of norbornenes generally gave a higher regioselectivity than the endo substituents.