Homo-Diels–Alder cycloadditions catalysed by cobalt–triphenylphosphine-zinc systems
作者:I-Farn Duan、Chien-Hong Cheng、Juan-Su Shaw、Sheng-San Cheng、Kuo Fu Liou
DOI:10.1039/c39910001347
日期:——
[Col2(PPh3)n]âzinc systems (n=1 or 2) exhibit high catalytic activity for the homo-DielsâAlder [2 + 2 + 2] cycloadditions of norbornadiene with various alkynes including terminal and internal acetylenes and methyl prop-2-ynyl ether to give the corresponding deltacyclenes in good to excellent yields.
Catalytic asymmetric induction in the homo Diels-Alder reaction
作者:Mark Lautens、Julia Craig Lautens、A. Catherine Smith
DOI:10.1021/ja00170a030
日期:1990.7
Asymmetrische Katalysen
作者:Henri Brunner、Franz Prester
DOI:10.1016/0022-328x(91)86338-q
日期:1991.8
The enantioselective homo Diels-Alder reaction of norbornadiene with monosubstituted acetylenes affords optically active deltacyclenes. The catalyst is a cobalt complex, which is prepared in situ from Co(acac)3, Et2AlCl, and optically active phosphines. With catalysts containing Norphos, a quantitative yield can be achieved for 4-phenyl- and 4-n-butyldeltacyclene with an enantiomeric excess of more than 98%. For some catalysts the solvent has a decisive influence on the chemical and optical yield.
Deltacyclene formation catalysed by cationic Co(II) complexes
作者:P. Binger、S. Albus
DOI:10.1016/0022-328x(95)05377-2
日期:1995.5
Alkynes and norbornadiene can be codimerized in a [2 + 2 +2] Homo-Diels-Alder reaction, yielding deltacyclenes. Instead of reduced Co species as used in former cases, Co(II)-complexes activated with Lewis acids such as ZnI2 or ZnCl2 are used to obtain the same products. The [CoI(PPh3)2]+ cation appears to be the catalytically active compound.