Asymmetric PdCl2/ DIOP

Asymmetric hydrocyanation has now been achieved using norbornene and norbornadiene as substrates. The reduction of either [PdCl2(+)-DIOP] or PdCl2 in presence of (+)-DIOP led to a palladium(O) species formulated simply as [Pd(+)-DIOP]. This gave, in reaction (164), an optical yield of 30% for the 2-exo-cyanonorbornane formed. Norbornadiene with the same catalyst gave 2-exo-cyanonorborn-5-ene with an optical purity of 17%. When the ligand CHIRAPHOS (51) was used, the catalytic activity was greatly diminished.608,609 In addition to the review of the early work already mentioned, two more recent reviews of hydrocyanation have appeared.610,611... 

Table VI. Comparison Between Experiments and Forecast for the Prevailingly Carbonylated Unsaturated Carbon Atom and for Absolute Configuration in Asymmetric Hydrocarbalkoxylation by PdCl2/(-)DIOP on the...

Other Pd Derivatives and Related Reactions. Other chiral palladium complexes, such as (DIOP)2Pd° or (DIOP)(alkene)Pd°, can be prepared from (DIOP)PdCl2. These catalysts have afforded low levels of asymmetric induction (10% ee) in the hydro-cyanation of norbomene derivatives. ... 

Oxirane Formation. The reaction of acetonyltributyltin with a-bromoacetophenone to yield 2-acetonyl-2-phenyloxirane has been investigated using ((-i-)-(2,S, 3,S )-DIOP)PdCl2 as a catalyst, but no asymmetric induction was observed. ... 

Carboxylic acids and their derivatives, esters, amides, anhydrides, and acyl halides, are formally synthesized from olefins, carbon monoxide, and compounds represented with HX where X- equals OR-, NR2-, etc (see Scheme 1). Considering that the chiral aldehydes obtained by asymmetric hydroformylation of viny-larenes are often oxidized in order to exhibit biological activities, asymmetric hydrocarboxylation and its related reactions naturally attract much attention. Unfortunately, however, as yet only less successful work has been reported on this subject than on hydroformylation. Palladium(II) is most commonly used for this purpose. Asymmetric hydrocarboxylation of olefins was first reported in 1973 by Pino using PdCl2 and (-)-DIOP [105]. Chiusoh reached 52% ee in the... 

Asymmetric Carbonylation Reactions.—Hydrofonnylation of Cgv alkenes [e.g. (Z)-MeCHCHMe] with [RhH(CO)(PPhs)3] + (-)-diop has been reported to yield a single aldehyde (3.8— 27% e.e.). J Cl2 (-)-diop ]-SnCl2 catalyses the hydrofonnylation of CH2=C(Ph)R (R = Me or Et). In contrast to a previous study, it is also reported that hydrofonnylation of but-l-ene, m-, or trans-but-2-ene with this catalyst gives different optical yields of 2-methylbutanal and therefore asymmetric induction takes place before the formation of metal-alkyl intermediates. [PdCl2(PhCN)2],L catalyses reaction (7) optical yields of... 

---