Reaction of formaldehyde with ammonia gives several kinds of products, including 3 : 3, 5 : 4, 6 : 4, and 7 : 6 adducts. The reaction of aldehydes with polyfunctional compounds having amino and hydroxy groups has been reported in the literature to produce a variety of unsaturated and saturated heterocycles. Detailed stereochemical studies on such monocyclic products using NMR spectroscopy have revealed that they are controlled by anomeric effects, repulsion of lone-pairs, 1, 3-interactions, and gauche effects. Recently preparations of novel polyazapolyheterocycles by reactions of mono- and dialdehydes with mono-, di-, tri-, and tetraamines, and diaminoalcohols have been reported. These reactions have resulted in interesting and unanticipated caged, bridged, and macrocyclic products whose stereochemistries have been examined by NMR spectroscopy. Some stereoisomers were found to be consistent with predictions by heats of formation using MOPAC and steric energies using MM calculations and have been subsequently confirmed by X-ray crystallography.
It was demonstrated that a series of fluoroalkylated end-capped oligomers containing various functional segments such as carboxy, amide, betaine, and hydroxy groups can be prepared by the use of fluoroalkanoyl peroxides as key intermediates. These thus-obtained fluoroalkylated end-capped oligomers were soluble in water and organic solvents, and were capable of reducing the surface tension of water effectively with a clear break point resembling a CMC, which is almost the same level as that achieved by the usual low molecular weight fluorinated surfactants. This is a unique and interesting feature of our fluoroalkylated end-capped oligo-surfactants. Furthermore, fluoroalkylated end-capped oligomers were suggested to form the molecular assemblies imparted by strong aggregation of the fluoroalkylated end-groups in aqueous solutions, and fluoroalkylated end-capped acrylic acid and sulfonic acid oligomers were also shown to be potent and selective inhibitors of human immunodeficiency virus type 1 (HIV-1) in vitro. More interestingly, fluoroalkylated end-capped oligomers containing betaine or hydroxy segments could cause gelation, where the synergistic interactions of both the strong aggregation of the end-capped fluoroalkyl segments and the ionic or hydrogen-bonding interaction are involved in establishing a gel network in water and polar organic solvents.
Transmetallation, generating organotransition metal species from alkylating reagent and metal complexes, plays important roles in many synthetic organic reactions catalyzed by transition metal complexes. This article describes recent progress in mechanistic study on the transmetallation and in elucidation of its relevance to synthetic organic reactions catalyzed by transition metal complexes. Pd complex catalyzed cross-coupling reactions of aromatic halides with organomagnesium and organotin reagents and with terminal alkynes involve transmetallation of alkyl and alkynyl group from the non-transition or transition metal compounds to Pd complexes. Ni (0) complex promoted dehalogenative condensation of aryl halides in DMF occurs via disproportionation of bromo (aryl) nickel (II) complexes to form diarylnickel complex which is responsible for reductive elimination of biaryls. Mechanisms of isomerization between cis- and trans-diarylpalladium complexes having auxiliary thioether ligand and of conproportionation of diorgano- and dichloro-complexes of group 10 metals are discussed.
Efficient and convenient methods for the synthesis of fluorinated alcohols have been required not only in organic synthesis but also in materials chemistry, because some of these compounds are applicable to the synthesis of various fluorine-containing substances of biological and material interest. Recently, the aluminum intermediates generated from esters and diisobutylaluminum hydride have successfully been employed as the synthetic equivalents of aldehydes, in the preparation of various types of secondary alcohols. This review describes the new approach to the methods for preparing fluorinated alcohol derivatives from fluorinated esters, together with the recent developments in organic synthesis based on such aluminum intermediates.
D-Alanine and n-tartaric acid are widely used for the intermediate of pharmaceuticals, the food additives, chiral building blocks and the resolving agents, etc. The industrial manufacturing method was not known in about year of the 1985 though D-alanine manufacturing method was researched by various methods. We designed the new, industrial manufacturing method by which selective assimilable ability of the microorganism was used. That is, the whole quantity L-alanine is assimilated if the microorganism which can assimilate L-alanine as a carbon source is cultured with DL-alanine medium, the organism in the medium becomes only D-alanine substantially, and the purpose is achieved to isolate of D-alanine from this medium. The merit of this method is a thing that D-alanine of a high optical purity can be manufactured from an easy operation. Candida was selected as a microorganism which agreed with the purpose and selective assimilation method was established as an industrial manufacturing method. As for the research of the industrial manufacturing method of D-alanine, after 1986 when it began to show signs, that demand expands as a medium of the sweeteners, it becomes active and an excellent manufacturing method in the fermentation and the enzymatic method has been developed. The selective assimilation method does not limit to D-alanine and be advantageous as the general manufacturing method of unnatural type amino acid. In addition, it is possible to apply also to the manufacturing method of unnatural type oxy acids such as n-tartaric acid.
The chiral building block approach to enantiomerically pure compound synthesis is known as “chiral pool method” and extensively employed for the synthesis of biologically interesting natural products. In spite of its great synthetic utility, frequently it becomes a serious problem to elaborate the side chain on the carbon center bearing a β-oxygen functionality. However, because of the electron-withdrawing nature of β-oxygen it is generally accepted that alkylation through nucleophilic displacement reaction is not so easy. In order to overcome this difficulty we have designed to use the trifluoromethanesulfonates (triflates) as extremely reactive substrates for the required carbon-carbon bond-forming reaction. That is, the alkylation of chiral triflate derivatives with Grignard or organolithium reagents provides a new rapid means for natural product synthesis and the method is termed as “chiral triflate technology”. In this article, total syntheses of (+) -exo-brevicomin, L-factor, the cyclohexyl fragment of FK-506, (+) -diolmycin A2, (+) -panaxacol, renin inhibitor, and AI-77-B starting from L- or D- tartaric acid or D-ribose as a chiral source are described.