carbene‐containing metallacyclic units and monodentate chiral phosphines have been prepared. The key step of their synthesis is the intramolecular oxidative addition of N‐2‐iodobenzylimidazolylidene‐platinum(0)‐diene complexes in the presence of the chiral phosphorus ligands. The platinum(II) metallacycles have been used as well‐defined pre‐catalysts for the enantioselective cycloisomerization of nitrogen‐tethered
Touch, Pauson, engage: To explain the unique superior reactivity and stereoselectivity of O‐tethered enynes in asymmetric Pauson–Khand type reaction (APKR) than their congeners, the internal‐chelation to metal of oxygen atom of the substrate in the transition state was proposed. This proposition was well supported by APKR with several different substrates.
phosphoramidites is a paracyclophane scaffold in which two aryl rings are tethered by both a 1,8‐biphenylene unit and a O−P−O bridge. Suitable aryl substituents generate planar chirality. The corresponding gold(I) complexes promote the cycloisomerization of prochiral nitrogen‐tethered dienynes. These reactions afford bicyclo[4.1.0]heptene derivatives displaying three contiguous stereogenic centers
Desymmetrization of meso-dienyne by asymmetric Pauson–Khand type reaction catalysts
作者:Nakcheol Jeong、Dong Hoon Kim、Jun Hun Choi
DOI:10.1039/b401288g
日期:——
Desymmetrization of the meso dienynes, such as propargyl 1-vinylallyl N-tosylamides (1aâc) and propargyl 1-vinylallyl ethers (1dâe), by asymmetric PausonâKhand type reaction catalysts was studied. The corresponding vinyl substituted bicyclic pentenones (2 and 3) were obtained with high diastereoselectivity and enantioselectivity.