Metal-catalyzed asymmetric processes offer one of the most straightforward ways to introduce stereogenic centers Hence, the development of novel chiral ligands that can effectively induce asymmetry in reactions is crucial in modern organic synthesis While many established chiral ligands bind to a metal through heteroatoms, structures that coordinate to metals through carbon atoms have received little attention so far Here, we highlight the increasing number of such chiral chelating olefin ligands as well as their application in a variety of metal-catalyzed transformations

Chiral olefins as steering ligands in asymmetric catalysis.

New Palladium Carbene Catalysts for the Heck Reaction of Aryl Chlorides in Ionic Liquids

New processes for the selective production of 1-octene

Organopalladium complexes containing palladiumpalladium bonds

A highly efficient catalyst for the telomerization of 1,3-dienes with alcohols: first synthesis of a monocarbenepalladium(0)-olefin complex.

The complexes (cod)MCl2 (M = Pd, Pt; cod = cis,cis-1,5-cyclooctadiene) react with Li2(cot) (cot = cyclooctatetraene) in a 1,6-diene/diethyl ether mixture (1,6-diene = hepta-1,6-diene, diallyl ether, dvds (1,3-divinyl-1,1,3,3-tetramethyldisiloxane)) to afford the isolated homoleptic dinuclear Pd0 and Pt0 compounds Pd2(C7H12)3 (1), Pd2(C6H10O)3·C6H10O (2‘; 2:  Pd2(C6H10O)3), Pd2(dvds)3 (3), and Pt2(C7H12)3 (4). When 1−4 are treated with additional 1,6-diene the equally homoleptic but mononuclear derivatives of type M(1,6-diene)2 (5−8) and with ethene the mixed alkene complexes (C2H4)M(1,6-diene) (9−12) are obtained in solution. Complexes 1−12 react with donor ligands such as phosphanes, phosphites, or tBuNC to give isolated complexes of types L−M(1,6-diene) (13−41), which have also been prepared by other routes. In all complexes the metal centers are TP-3 coordinated:  complexes 1−4 contain chelating and bridging 1,6-diene ligands, whereas the other complexes contain a chelating 1,6-diene ligand and an η2-a...

1,6-Diene Complexes of Palladium(0) and Platinum(0): Highly Reactive Sources for the Naked Metals and [L−M0] Fragments

A palladium-catalyzed (2 + 2 + 1) cycloaddition reaction of two C2H2 and one SnR2 to form C-unsubstituted stannoles (C4H4)SnR2 [R = CH(SiMe3)2 2a, R2 = {C(SiMe3)2CH2}2 2c] is described. Catalysts are (R‘2PC2H4PR‘2)Pd complexes (slow reaction) and (R‘3P)2Pd complexes (fast reaction). The mechanism of the catalysis has been elucidated in detail from stoichiometric reactions based on R = CH(SiMe3)2. For the [(R‘2PC2H4PR‘2)Pd]-catalyzed system, the starting Pd(0)−ethene complexes (R‘2PC2H4PR‘2)Pd(C2H4) (R‘ = iPr (3), tBu (4)) react both with ethyne to give the Pd(0)−ethyne derivatives (R‘2PC2H4PR‘2)Pd(C2H2) (R‘ = iPr (5), tBu (6)) and with SnR2 to yield the Pd(0)−Sn(II) adducts (R‘2PC2H4PR‘2)PdSnR2 (R‘ = iPr (7), tBu (8)). The Pd−Sn bond [2.481(2) A] of 7 is very short, indicative of partial multiple bonding. Subsequent reactions of the Pd(0)−ethyne complexes 5 and 6 with SnR2 or of the Pd(0)−Sn(II) complexes 7 and 8 with ethyne afford the 1,2-palladastannete complexes (R‘2PC2H4PR‘2)Pd(CHCH)SnR2 (Pd−Sn) (R‘ =...

A Palladium-Catalyzed Stannole Synthesis

The two N donor atoms in the tertiary diamine N,N‘-dimethyl-3,7-diazabicyclo[3.3.1]nonane (dabn, C9H18N2) are ideally positioned in the bicyclic structure for chelation to a metal center. This feat...

Karl-Josef Haack

Papers

1,6-Diene Complexes of Palladium(0) and Platinum(0): Highly Reactive Sources for the Naked Metals and [L−M0] Fragments

A Palladium-Catalyzed Stannole Synthesis

Applying the Macrocyclic Effect to Smaller Ring Structures. N,N‘-Dimethyl-3,7-diazabicyclo[3.3.1]nonane Nickel(0) Complexes

Novel (R2PC2H4PR2)M0−COT Complexes (M = Pd, Pt) Having Semiaromatic η2-COT or Dianionic η2(1,4)-COT Ligands

Hepta-1,6-diene and diallyl ether complexes of palladium(0) and platinum(0):a route to L–M(alkene)2 complexes containing non-activated alkenes