Advances in structural organic chemistry in the past have been reviewed. In the past, intramolecular interaction was the main topic in structural organic chemistry as well as the synthesis of strained molecules and unusual compounds which have contributed to the advance in understanding of chemical bonding. In recent years, the interest of structural organic chemists seems to be changing from intramolecular to intermolecular interactions : reactions are now the target of study in this field. Incipient transition state which can be modeled by certain congested molecules and conformational effects on reactivity are cited. Quantitative understanding of the steric effect and the solvent effects on the molecular levels are the remaining problems in this field. Methodology, both theoretical and experimental, which potentially contributes in studying these problems is discussed.
The recent developments of organic photochemistry in organic synthesis, chemical conversion of solar energy, approaches to photobiological problems, applications to information technology and others, are briefly surveyed.
The past and the present of the electroorganic chemistry have been described from the standpoints of organic synthesis and industrial application. Three typical characteristics of the electroorganic chemistry, that is, umpolung, nature of electrified interface, and mediator have been briefly explained, and the future of the electroorganic chemistry has been viewed from these three aspects.
Advances and trends of heterocylic chemistry are discussed focussing mainly in 1981 in reference with chemical abstracts. The contents are divided into 1 introduction, 2 reviews and books, 3 new heterocycles, 4 new synthetic methods, 5 conclusion.
Organic synthesis today is briefly described based on the IUPAC 4th ICOS (International Conference on Organic Chemistry). New methodologies and syntheses of important substances which were discussed by Plenary and Invited Lecturers in 4th ICOS are discussed.
The concept of combined acid-base attack is important for understanding the behaviour of R3Al or R2AlX type reagents as well as to explore further synthetic applications. The topics will involve such molecular rearrangements as Clisen type, pinacol-pinacolone type, and alk-5-en-5-olides-cyclohexane-1, 3-diones type. All rearrangements are induced by the action of organoaluminium reagents and the former two proceed under uptake of nucleophiles from aluminium on the carbonyl carbon. Reaction of enol phosphates with organoaluminium reagents is catalyzed by Pd (PPh3) 4 complex to produce C=C-R type products.
Recent progress in organic synthesis using transition metal complexes is reviewed. Emphasis is made particularly on (1) reactions based on the nucleophilicity and reducing ability of low-valent metals, (2) organo-copper chemistry, (3) reactions caused by the electrophilic activation of π-ligands by electron-deficient metal moieties, and (4) reactions of metal-carbenoids. The mechanistic aspects are also discussed briefly.
This article describes the recent advances in asymmetric synthesis using homogeneous optically active metal-complex catalysts briefly. The methods for asymmetric induction are discussed in relation to the characteristics of the reactions with transition-metal complexes.
Utility of a chiral glycerin derivative [(S) -1] as a versatile substrate for the enantioselective syntheses of natural products is described. The glycerin derivative [(S) -1] is converted into both enantiomers of the chiral γ-butyrolactone (3) which are in turn transformed to a -monosubstituted lactones (31) and α, α -disubstituted lactones (34) by stereoselective alkylation under kinetic conditions. Inversion of the α center of the monoalkylated lactone 31 is simply achieved by brief exposure of the enolate (32) derived from 31 to saturated aqueous sodium sulfate solution to give (33). α-Aryllactone derivatives (28) which cannot be obtained from the lactone substrate (3) are efficiently prepared from the epoxide (2) obtained from the glycerin derivative (1) and an appropriate phenylacetonitrile. Using the lactone intermediates thus obtained, a dozen of optically active compounds ranging from monoterpenes and alkaloids to a β-lactam derivative illustrated in Fig. 1 are synthesized enantioselectively.
Recent developments in the chemistry of sugar-containing antibiotics are briefly surveyed from the standpoint of synthesis. The antibiotics are classified into 1) aminoglycoside antibiotics, 2) macrolide antibiotics, 3) anthracycline antibiotics, and 4) others. Total syntheses of aminoglycoside antibiotics have been developed as exemplified by those of streptomycins, kanamycins, neomycin C, and spectinomycin. Several semi-synthetic aminoglycoside antibiotics which are active against resistant bacteria have been developed and commercialized. Total syntheses of several macrolide antibiotics have recently been completed as exemplified by those of methymycin, erythromycin, carbomycin B, and josamycin. Very recently, 23-dialkylamino-derivatives of mycarosyl and 4' - deoxymycarosyl tylonolide were synthesized and found remarkably active against · Gram-negative bacteria, Total syntheses of the representative anthracycline antibiotics, adriamycin and daunomycin have been completed, and syntheses of their derivatives of improved toxicity are in active progress. In the other area, total syntheses of bleomycin, an important antineoplastic agent, and streptothricin, a well-known antibacterial antibiotic, have recently been completed. Several approaches to ward the total syntheses of antibiotics containing sugars are cited.
1. Brief history of total syntheses of natural products. 2. Total syntheses are likened to mountain climbings. 3. Purpose of the total syntheses of natural products. 4. Total syntheses of natural products having polyfunctional groups. 5. Epilogue.
Biomimetic chemistry, particularly in Japan, is reviewed based on the special project research “Biomimetic Chemistry” supported by Ministry of Education, Science and Culture. Emphasis is made on the synthetic applications and the future aspects of this field.
Vitamin B12-dependent enzymes catalyze various methyl transfer reactions and isomerizations accompanied by the initial 1, 2-shift rearrangement. Adenosylcobalamin, which involves both metal-coordinate and organometallic bonds in the same molecule, acts as a true catalyst in the latter reactions. Coenzyme reaction machanisms have been extensively investigated particularly in connection With methylmalonyl-CoA mutase and diol dehydrase, and homolytic cleavage of the Co-C bond as well as its heterolytic cleavage to yield a carbanion intermediate has been postulated. Since cob (I) alamin and its model compounds in Co (I) state act as supernucleophiles, various reactions as catalyzed by these complexes have been examined. For the establishment of effective B12 holoenzyme models, synthetic lipids which form stable single-walled bilayer aggregates in aqueous media are plausibly adopted as apoenzyme models. Novel organometallic chemistry is hopefully developed in the light of biomimetic notions.
A chemical firm should generate profit by the development of innovative technologies and new products of its own, which can in turn generate resources for future research and development. This has been the case in Europe and in the United States. On the contrary, management of the Japanese chemical industry has been guided by so called “the spirit of business”, i. e. Japanese chemical companies have been trying to generate profits mainly from commercial transactions of commodity chemicals, by paying little attention to the importance of basic R & D. This seems to be the major reason as to why the development of truly innovative technology has not been successful in the Japanese chemical industry. I believe that it is a prerequisite for the Japanese chemical industry to liquidate such mercantilistic thinking and establish a new managerial philosophy, i. e. the chemical firm should achieve its growth and development through the creation of own innovative technologies.
Organic chemical industries are now in bad situation in Japan. The most intelligible example is petrochemicals and are decreased their production about 30 or 40 percent. In spite of such worse conditions in industries, fundamentel researches in organic chemistry and biosciences have won fruitful successes in these twenty years. So we must proceed forward in organic chemical industries, applying such iruitful successes. The key will be creations through R & D and depends on how we can get market.
After a brief historical survey of organic synthetical industry in Japan, the author described that the cause of the present stagnation is owing to the lack of new commercial products and the rising cost of raw material. As a countermeasure, the author mentioned that research of new material and new device, and research work of new synthetic method concerning C1-chemistry, namely, new synthetical chemistry are the key technology for saving the present situation.
(1) The characteristics of biochemical reaction are compared with those of organic chemical reaction, and the advantages of the former reaction are discussed. (2) As the immobilization of biocatalysts has been the subject of increased interests, the immobilization procedure and the advantages of immobilized biocatalysts are reviewed. (3) Industrial applications of biochemical reaction for the production of following useful, compounds are presented : optically active amino acids, peptides, optically active organic acids, steroids, and others.