Results of thermodynamic and kinetic studies so far reported are summarized on the complex formation of saturated macrocyclic tri- (9 membered), tetra- (1215 membered), and penta- (1517 membered) amines with several matal ions such as Cu, Zn, Cd, Hg, and Pb. Together attached are data for closely related linear polyamine reactions. Comparisons are made between macrocyclic and linear systems, between macrocycles with different ring size, and between different metal ions, in order to discuss the effects of ligand cyclization, macrocycle ring size, and change in metal ions on the equilibria and kinetics of the complex formations. Some of the conclusions and postulates reached from the macrocyclic polyamine studies seem relevant to other macrocyclic systems including “crown ethers”.
The biomimetic synthesis of some spirodienone-type natural alkaloids (oxocrinine, oxomaritidine, amurine, flavinantine, pallidine, cryptopleurine and colchicine etc.) by anodic oxidation is reviewed. The effectiveness of fluoboric acid as electrolyte in the electrochemical synthesis of some spirodienones is also described.
This review represents an attempt to provide an up-to-date introduction to the pyrrolizidine alkaloids which have highly cytotoxic activities. Numerous naturally occurring pyrrolizidine alkaloids are grouped systematically and the structural elucidation of a few alkaloids are discussed in detail. Their chemical synthesis and biosynthesis are also covered.
Ethyl octyl sulfide was prepared by the reaction of 1-octanethiol with ethyl bromide in the presence of quaternary ammonium halide. The appropriate quaternary ammonium salt such as (n-C12H25) 3N+C2 H5Br- was found to be effective as the phase-transfer catalyst and the sulfide was obtained almost quantitatively in about 15 minutes.
Effects of additives on the asymmetric yield of methyl 3-hydroxybutyrate were examined in the hydrogenation of methyl acetoacetate using Ni-Pd-Kieselguhr catalyst modified with tartaric acid. Addition of unsaturated compounds such as dehydroacetic acid and diethyl maleate showed almost no effect on the asymmetric yield. Only when carboxylic acids having pKa values higher than that of tartaric acid such as formic acid, acetic acid, benzoic acid, and succinic acid were used as additives, great increase in asymmetric yield was observed.
Hydrozirconation using chlorobis (η-cyclopentadienyl) hydridozirconium (IV) (1) has recently been developed as a procedure for functionalizing alkenes, alkynes, and 1, 3-dienes via organozirconium (IV) intermediates. These intermediates react with a variety of electrophilic reagents to give organic products in high yield. Via transmetalation the zirconium intermediates also serve as, precursors of reactive organometallic complexes of metallic elements whose chemistry is well established with regard to C-C bond formation processes. Synthetic and mechanistic aspects of organozirconium chemistry are discussed.
Oxo synthesis or hydroformylation for the production of aldehydes and alcohols has become more important as the demand for plasticizers and detergents increases. Many processes using the homogeneous Co catalyst were well-established and have brought the big industrial success. The phosphine-modified Co catalyst used in Shell Process has led to high proportions of straight chain isomers in the product. Recently, the new oxo process for making butyraldehydes and propionaldehyde was commercialized by UCC. This technique is characterized by a phosphine-modified Rh catalyst that results in high product selectivity at low capital and operating costs.