Recent developments concerning homogeneous catalysts stimulate new interest in the field of synthetic organic chemistry. In particular, metal cluster as homogeneous catalysts offer not only better and more selective catalyst for the synthetic reactions, but also useful models in the study of chemisorption and heterogeneous catalysis. Metal cluster compounds contain three or more metals bonded to each other forming triangular, tetrahedral, octahedral and other polyhedral molecular structures. Application of metal clusters as catalyst is especially welcome in these days when the chemical industry should seek ways to conserve energy and resources. In this context, the following synthetic reactions by means of metal clusters are introduced in this review : hydrocarbons and alcohols from synthetic gas, oxidation reaction, dehydrogenation and isomerization, hydrogenation (especially by Ni-isonitrile cluster), dimerization, hydroformylation, carbonylation, Reppe reaction, water gas shift reaction, anchored metal cluster catalysis, peculiar cluster compounds and the ligand mobility within clusters.
Recent applications of molecular mechanics calculations to organic conformational analysis are reviewed. Static conformational aspects of the following compounds are discussed : saturated hydrocarbons including n-hexadecane, di-t-butylethane and 1, 1, 2, 2- tetra-t- butylethane, cycloalkanes including 1, 2-di -t- butylcyclohexanes, nonconjugated olefins including cyclodeca -1, 6- diene and tetra -t- butylethylene, aromatics and conjugated olefins including bianthrone, polyarylated ethanes, hexaphenylethane, cyclophanes, 1, 3, 6, 8-tetra-t- butylnaphthalene, systems containing hetero atoms such as oxygen, halo and silicone, and biologically interesting molecules including steroids and cyclotetraglycyl. Dynamic conformational aspects including internal rotation, pseudorotation and racemization of metacyclophane,  helicene and 1, 1'-binaphthyl, and flexibility of bicyclo [3.3.1] nonane and bicyclo [3.3.2] decane are also discussed.
Separating the stereospecific factor from others governing the manifestation of biological activity to estimate its relative significance is the first step in understanding the stereospecific effect of biologically active compounds. In certain cases, this can be performed by means of quantitative structure-activity-relationship of congeneric series of bioactive compounds using physical-organic models and multiple regression analysis. Examinations were made for the use of the Taft Es and the Hancock Esc parameters as the model of intra- as well as inter-molecular steric effects. Quite a few congeneric series of bioactive compounds were successfully analyzed using these free -energy-related parameters. The comparison was made with other steric parameters currently used in structure-activity studies.
Syntheses and reactions of aminoalkylsilanes are reviewed on the follwing items : aminomethylsilanes, β-aminoethylsilanes, β-aminovinylsilanes, aminoethynylsilanes (silylynamines), and hetrocyclic compounds containing nitrogen and silicon atoms.
Various synthetic reactions applied by the Pummerer reaction are described. Many examples for syntheses of carbonyl compounds, such as aldehyde, α- hydroxyaldehyde, α- ketoaldehyde, diketone and carboxylic acid derivatives, are given. Syntheses of heterocycles applied by an intramolecular Pummerer reaction and several interesting Pummerer reactions of vinyl sulfoxides are also described.