Chemoselective Reactions of (<i>E</i>)-1,3-Dienes: Cobalt-Mediated Isomerization to (<i>Z</i>)-1,3-Dienes and Reactions with Ethylene
作者:Yam N. Timsina、Souvagya Biswas、T. V. RajanBabu
DOI:10.1021/ja501979g
日期:2014.4.30
In the asymmetrichydrovinylation (HV) of an E/Z-mixture of a prototypical 1,3-diene with (S,S)-(DIOP)CoCl2 or (S,S)-(BDPP)CoCl2 catalyst in the presence of Me3Al, the (E)-isomer reacts significantly faster, leaving behind the Z-isomer intact at the end of the reaction. The presumed [LCo–H]+-intermediate, especially when L is a large-bite angle ligand, similar to DIOP and BDPP, promote an unusual isomerization
Back to the first row: A surprisingly simple protocol involving chiral diphosphine complexes of cobalt(II) salts allows the highly enantioselective hydrovinylation of 1,3‐dienes in extremely high selectivities and yields.