In order to rationalize and correlate a variety of chemistry exhibited by heteroatoms, “heteroatom effect”, a new term, is proposed and its meaning is defined with the emphasis on the role of an unshared electron pair. For the first row heteroatoms (N, O), heteroatom effect is confined to the effect of unshared electron pair and the latter is classified into the ability to stabilize carbocations due to stereoelectronic effect of Deslongchamps sense and the ability to coordinate with metal cations, especially with lithium ion, to effect ortho-lithiation and to generate pseudo-five membered ring intermediates for controlling stereoselectivity. For the 2nd, 3rd, and 4th row heteroatoms of IVB, VB, VIB and VIIB groups, heteroatom effect is classified into three effects on the basis of i) role of unshared electron pair, ii) role of valence expansion of the central atom, and iii) role of low lying orbital of σ*c-x. Importance of electron-rich and polarizable three-center four-electron bond is implicated to explain the geometry and reactivity of σ- and π- hypervalent molecules.
Since 1965 we have been studying the synthesis of (2 S) -2- aziridinecarboxylic acid (Azyline, (2S) -Azy) or (2 S, 3 S) -3-methyl-2- aziridinecarboxylic acid ((2 S, 3 S) - 3-MeAzy) derivatives. Azyline is relatively labile compound, however azyline placed in the peptide chain become stable and is very easy to handle. They still retain their reactivity, due to the Azy residue, against the protic reagents such as acids, bases, alcohols or thiols. Thus, Azy derivatives can be widely used for peptide chemistry. This paper describes the synthesis, the reactions, the physicochemical properties, and the uses of Azy derivatives.
Substituted and unsubstituted dioxo  aneN5 (1, 4, 7, 10, 13-pentaazacyclohexadecane-14, 16- dione) form stable 1 : 1 square pyramidal complexes with Ni (II), which posess two deprotonated amide donors in equatorial positions. The high spin Ni (II) complexes show very low NiII, III redox potentials +0.24V vs. SCE and react with molecular oxygen to from 1 : 1 Ni (III) -O-2 adducts in aqueous solution. The oxygen adducts hydroxylate electron- rich aromatic compounds to form phenol derivatives. This is a good model reaction of biological aromatic hydroxylation since the oxygen atom incorporated into aromatic rings is entirely from molecular oxygen.
New syntheses of naturally occurring quinones with high physiological activities are described in this review. Synthetic strategies of these quinones are based on the regio- (and/or stereo-) selective introduction of allylic or 2, 4-pentadienyl side chains directly to quinones with the corresponding organosilanes and -stannanes. This review contains the following topics; (i) allylorganostannanes as efficient allylating reagents to quinones, and regio- and stereoselective synthesis of polyprenylquinones, i. e. coenzyme Qn, vitamin K, (ii) methyl 2-triorganosily1-3-butenoate as a new synthon of 3-methylcarbonylallyl anion and its application to the synthesis of pyranonaphthoquinone antibiotics, i. e. (±) -nanaomycin A, (±) -deoxyfrenolicin, (iii) biomimetic AB ring synthesis of an aglycone of an anthracycline antibiotic, aklavinone, by means of intramolecular electron relay system, (iv) synthesis of 11-deoxydaunomycinone precursor by means of intramolecular Diels-Alder reaction, (v) novel synthesis of pyrrolo [1, 2-a] -indol-5, 8-quinone by means of intramolecular cyclization and application to the synthesis of mitosenes.
Recent developments in the field of oligodeoxyribonucleotide synthesis were described. Novel coupling systems such as new condensing reagents for modified phosphotriester method, phosphite coupling and its modified method, and activated phosphotriester method were discussed. On the other hand, newly developed protective groups of guanine and adenine moieties, partial deprotection systems for trityl groups, and widely developed polymer support synthesis were also described. The efficiency of these methods was obvious in terms of yields and time, so one can construct a defined oligodeoxyribonucleotide more easily and rapidly. And further investigation of the deprotection and purification systems by using high performance liquid chromatography let us obtain the pure DNA fragments.
Since 1960's, many kinds of microorganisms have been reported which are able to utilize various kinds of hydrocarbons and their derivatives. These microorganisms have been considered to be useful for their abilities of not only decomposing various organic pollutants in natural environment but also producing cellular materials and metabolites. Recently, however, decreased number of the reports appear to be published on the fermentations performed with hydrocarbons as substrate, mainly because of the elevated cost of those substrates. Thus, the investigations of hydrocarbon fermentation are now focused on the products which are formed from hydrocarbons in preference to conventional substrates such as carbohydrates, and some of them, for example, the production of long chain dicarboxylic acids are already industrialized. In this review, recent papers on the microbial utilization of gaseous hydrocarbons, long chain aliphatic and isoprenoid hydrocarbons and their derivatives are summarized, especially from the applied point of view.
C1-compounds, especially methanol, are recently attracting much attention as convenient raw material in the wide variety of biotechnology fields not only for single cell protein production but also for productions of fine chemicals and commodity chemicals. A kind of attempts have been per-formed to establish the new process for the fermentative production, in which both the unique and conventional metabolisms of methylotrophs are utilized. These include processes for the production of single cell protein, amino acids, vitamins and coenzymes, enzymes, epoxides, methylketones and formaldehyde. In this review, these attempts are introduced together with fundamental background on the unique features of microbial metabolism of methanol and other C1-compounds.