Highly Selective Cobalt‐Catalyzed Hydrovinylation of Styrene

Abstract

Phosphine complexes of cobalt halide salts activated by diethylaluminum chloride are shown to yield highly active catalysts in the hydrovinylation of styrene, with unprecedented high selectivity to the desired product 3-phenyl-1-butene (3P1B). Doublebond isomerization, a common problem in codimerization reactions, only occurs after full conversion with these catalyst systems, even at elevated temperature. The most active catalysts are based on cobalt halide species combined with either C 1 -or C 2 -bridged diphosphines, heterodonor P,N or P,O ligands, flexible bidentate phosphine ligands or monodentate phosphine ligands. Kinetic investigations show an order > 1 in catalyst, which indicates either the involvement of dinuclear species in the catalytic cycle or partial catalyst decomposition via a bimolecular pathway.

Catalytic Intermolecular Tail‐to‐Tail Hydroalkenylation of Styrenes with α Olefins: Regioselective Migratory Insertion Controlled by a Nickel/N‐Heterocyclic Carbene

“…[2][3][4] Although more functionalized conjugate carbonyls and dienes are used as one of the partners, [5,6] the direct addition of monoenes to these systems is also an important advance in the field. [7,8] Recently, some of these alkene coupling technologies have been developed to achieve the asymmetric synthesis of biologically important molecules, with ibuprofen being a representative example.…”

Asymmetric Hydrovinylation of Unactivated Linear 1,3-Dienes

“…However, surprisingly little attention has been paid to the Co-catalyzed codimerization of ethylene with other alkenes in which chiral branched products are formed. Only reported examples pertain to the high-pressure Fe(0)-catalyzed heterodimerization of ethylene (hydrovinylation) with ( E )-1,3-pentadiene (37% ee) and 2-methyl-1,3-pentadiene (31% ee)2c and a recently reported Co-catalyzed (also high pressure) hydrovinylation of styrene (50% ee) 6. Both Ru7 and Ni-catalyzed8–10 hydrovinylation reaction of 1,3-dienes have been reported, even though high enantioselectivity has been realized only for very limited substrates 9,10.…”

Transition‐Metal‐Catalyzed Laboratory‐Scale Carbon–Carbon Bond‐Forming Reactions of Ethylene

“…[45] In this report, the use of ( S,S )- 53 [( S,S )-diop] or ( S,S )- 54 [( S,S )-dipamp] resulted in moderate activity and low enantioselectivity (Scheme 17). The use of ( R,R )- 55 [( R,R )-dach] led to a promising near-doubling of the enantioselectivity, to 47% ee .…”