Methods for preparations of protein-protein and protein-hapten conjugates are reviewed from the view point of selective formation of the conjugates. The methods are classified into four types depending upon the chemical structures of the modifiers of proteins. The specific methods applied for mono-functional haptens having a carboxylic acid, amino or thiol group and non-specific ones used for polyfunctional modifiers in aids of homo-bifunctional reagents. The selective method utilizing the structural specificities of the protein and also the newly developed selective methods using hetero-bifunctional cross-linkers such as the maleimide succinimidyl ester type are discussed.

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Syntheses and reactions of organometallic compounds having Si-Mtl bond as well as “metal free” silyl anion species are reviewed in the order of the periodic classification of metal elements. With these reagents, silyl groups are successfully introduced into organic substrates by (1) substitution of halogen of alkyl, allyl, aryl, vinyl, and acyl halides, (2) addition to ketone and aldehyde carbonyls, and (3) addition to alkynes, allenes, and conjugated dienes. These reactions are useful for synthesis of versatile organosilicon compounds.

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Recent studies on the chemistry and structure-activity relationships of N-acetylmuramoyl-L-alanyl-D-isoglutamine, which is the minimal, immunoadjuvantactive structure of (a) replacing whole bacterial cell in complete Freund's adjuvant for increasing levels of antibodies against a given antigen, and (b) inducing a delayed-type of hypersensitivity, and its analogs, and of lipid A component of the endotoxic, bacterial lipopolysaccharide (LPS), will be reviewed.

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In this article the author explains recent advances and trends in the researches of polymer supported catalysts. First, he discussed the problems in commercialization of the polymer supported catalyst, namely ; separation & stabilization of the catalyst, acceleration of diffusion of reactants in the catalyst. Second, new polymer supports and reaction systems are introduced, which have been developed in order to accelerate the reaction. Third, polymer supported catalysts in a broad sense are classified into seven categories, and four of them are discussed about their specificities. Finally, sequential multistep reaction, asymmetric reaction, and macrocyclization are described as examples of the cases where the results of the reaction are controlled by the “polymer effect” of the ligand.

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Oligomers are the low-molecular-weight members of polymeric compounds in the molecular weight range from a few hundred to several thousand. Because of their unique physical properties, clearly differing from those of conventional low-molecular-weight compounds and high polymers, oligomers are currently used in many practical fields. This review summarizes methods for oligomer synthesis, primarily by addition oligomerization, and ralated reactions.
The scope of this review encompasses (i) the principle and examples of the synthesis of “telechelic” oligomers with a functional group at both chain-ends by addition (radical, cationic, anionic, and group-transfer) oligomerizations ; and the preparation of telechelic oligomers with ethynyl terminals and linear phenol-formaldehyde oligomers; (ii) the synthesis of “macromers” (oligomers having a polymerizable end-group) by ionic and radical mechanisms and their polymerization reactivity ; and (iii) the synthesis of cyclic or cyclic unit-containing oligomers. Problems in these oligomer syntheses are also discussed briefly.

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This article deals with the synthetic utility of dioxopyrrolines in the field of heterocyclic chemistry, especially on focusing carbon-carbon bond forming reactions, in which they acted as dienophiles on Diels-Alder reaction and also as enophiles on photocycloaddition reaction yielding hydroindoles and 2- azabicyclo [3. 2. 0] heptanes respectively. The latter compounds, strained cyclobutanes, underwent skeletal rearrangements to form various heterocyclic compounds such as hydroindoles, azatropolones, azanorbornenes, azanonanes, dihydropyridones, and dihydropyridines. This methodology was successfully applied to total synthesis of erythrina alkaloids.

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Phosphinothioic acid has tetrahedral structure in which the phosphorus atom becomes chiral center and the hydrogen oxide group has strong hydrogen bonding power. Fortunately, it is readily resolved into two enantiomers, which are stable to treat. The optically active phosphinothioic acids, especially phenyl-t-butylphosphinothioic. acid (1), can induce chemical shift non-equivalence of enantiomers in the ¹H NMR spectra of chiral compounds such as phosphinates, phosphonates, phosphine oxides, phosphinic amides, phosphinothioic acids, phosphonothioic acids, amines, and alcohols. The non-equivalence is due to the formation of diastereomeric complexes in which optically active acid is hydrogen bonded to the phosphoryl, amino, or hydroxy groups of the enantiomers.
Thus, the enantiomeric purities can be easily and accurately determined from the relative intensities (peak heights) of the two signals. Preparation of the thioacid (1) and recovery from the NMR solution are described in detail with the chemical shift non-equivalence data.

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