Our recent study on oxygenation and carbon-carbon bond forming reaction of olefinic compounds using a series of cobalt (II) catalysts have been descrived in the following four reactions. (1) Catalytic hydration of olefins with molecular oxygen and 2-propanol is performed by using bis (1, 3-diketonato) cobalt complex (Oxidation-Reduction Hydration). (2) The above cobalt (II) complex efficiently promoted the novel peroxygenation of a wide range of olefinic compounds with molecular oxygen and triethylsilane to afford the triethylsilyl peroxides in high yields. (Triethylsilylperoxygenation) (3) The cross coupling reactions of α, β-unsaturated compound with aldehyde and phenylsilane proceed in the presence of the cobalt (II) catalyst to give the aldol-type product. (4) Under the similar condition, catalytic oximation of α, β-unsaturated compound is achieved by using butylnitrite as an electrophile. The synthetic applications and a possible reaction path-way are also described.
Palladium-catalyzed carbonyl allylation by allylic alcohols with SnCl2 smoothly proceeds in aqueous medium under air. The actual allylating agent in the carbonyl allylation by allyl alcohol in dry medium is allyltrichlorotin, which is prepared via (1) oxidative addition of allyl alcohol to Pd (0) complex with SnCl2, (2) insertion of SnCl2 to π-allylpalladium complex, followed by (3) reductive elimination of π-allylpalladium trichlorostannate. Allylic alcohols, preparing π-allylpalladium complexes, function as synthons of allylic carbanions. In other words, this implies the apparent charge reversal of electrophilic π-allylpalladium complexes. The carbonyl allylation by allylic alcohols can achieve high chemo-, regio-, and diastereoselection by the choice of solvent, and can be applied to chelation-controlled diastereoselection in polar solvents.
Any reaction that results in ring formation can be of considerable potential use in organic synthesis. Nucleophilic center introduced through various kinds of lithiation undergoes intramolecular bond-forming reaction with the internal electrophilic center. Furthermore, the lithiated intermediate generated in this reaction reacts with various electrophiles to afford the products which have the substituents originated from electrophiles. This paper reviews the intramolecular cyclization reaction initiated through organolithium compounds.
Molecular design of biofunctional catalysts and photocatalysts for stereoselective molecular recognition was surveyed on the basis of our recent works on the design of enzyme (or metalloenzyme) -mimetic catalysts, photocatalytic chiral transition-metal complexes, and catalytic antibodies. The key concept for the present molecular design of highly active and stereoselective catalysts was derived from the transition-state control of enantiodifferentiating reactions. A typical example was indicated through the molecular design of highly active and stereoselective di- or tripeptide catalyst (including L-histidine moiety) for hydrolyzing enantiomeric amino acid esters. The extent of catalytic and stereoselective abilities of chiral manganese (II, III) porphyrins and ruthenium (II) tris (bipyridine) complexes was also tested in tryptophan-2, 3-dioxygenase and photo-induced electron transfer reactions, respectively. Finally, essential importance of reaction dynamics analysis was emphasized by taking notice of catalytic antibodies designed for recognizing the transition-state of reaction as an artificial enzyme.