Naturally occurring compounds containing -hydroxy-ß-amino acids have been presented in the first part of this review. The second part gives a summary of the more recent developments in the synthesis of enantiomerically and diastereomerically pure -hydroxy-ß-amino acids. Application of new strategies useful in the preparation of peptides with -hydroxy-ß-amino acids is also presented.

Phase diagrams in the CuGaSe₂-HgSe and CuInSe₂-HgSe systems have been constructed using differential thermal, X-ray phase and microstructural analyses. The CuGaSe₂-HgSe system is of the peritectic type. Solid solutions of the constituent components have been found and their limit compositions have been established. They contain 0-3 and 63-100 mol.% HgSe at 870 K. The CuInSe₂-HgSe system is of the first type, due to Roozeboom classification. A continuous range of solid solutions exists between HgSe and the high-temperature ß-modification of CuInSe₂. The solid solutions are created on the basis of -CuInSe₂ which contains up to 7 mol.% HgSe at 870 K.

Complexes of ZnX₂ (X = Cl, Br, I, SCN) with 5,7-dimethyl-1,2,4-triazolo-[1,5a]-pyrimidine, 5,7-diphenyl-1,2,4-triazolo-[1,5a]-pyrimidine and 5,7-di-tert-butyl-1,2,4-tri-
azolo-[1,5a]-pyrimidine were prepared and characterized by IR (100-4000 cm^-1) and ¹H, ¹³C, ¹⁵N NMR spectroscopies. Spectral data suggest pseudo-tetrahedral configuration around Zn(II) atom with N-3 bonded heterocycles. Halides and thiocyanates (N bonded) are in terminal positions.

Isothiocyanate 1 reacted with enaminone 2 to give thioamide 3 that cyclized by sodium hydroxide to pyrimidine 4 but cyclized by bromine to give isothiazole 5, pyrimidine 4 was transformed into thiopyranopyrimidines 7, 9 or 11 upon respective reaction with benzaldehyde, maleic acid, or maleic anhydride. Aminative cyclization of 4 yielded isothiazolopyrimidine 13. Reaction of 4 and ethyl bromoacetate or phenacyl bromides afforded thienopyrimidines 15a-b respectively. Oxidation of 4 yielded oxopyrimidine 16.

Thermal decomposition of 2,5-dihydro-1,3,4-thiadiazoles (1) in the presence of imidazole, pyrazole, 3-phenylpyrazole, and 1,2,4-triazole, respectively, yielded S,N-acetals of type 4. Interception of initially formed thiocarbonyl ylide 2 by the NH-azole is proposed as the reaction mechanism. Treatment of the S,N-acetals 4 with Raney-Ni gave N-substituted azoles 6.

Reactions of 2,4-disubstituted thiosemicarbazides with acetone catalyzed by sulfuric acid gave cyclic 1,2,4-triazolidine-3-thione derivatives. The same reaction with no catalyzer gave open-chain compounds. Synthesis and X-ray studies of some 1,2,4-triazolidine-3-thiones are described.

Reaction of 4(5)-bromo-2-methyl-5(4)-nitroimidazole with phenacyl bromide derivatives gave two isomers: 4-bromo-5-nitroimidazoles (4a-e) and 5-bromo-4-nitroimidazoles (5a-e). Compounds 5a-e were treated with cyclic secondary amines to afford expected 5-amino-4-nitroimidazole derivatives 6a-c - 10a-b.

Three polypeptide fragments of Hepatitis C virus protein (130-140)C, (133-142)C and (1406-1415)NS3 were synthesized using the solid-phase method. The immunogenicity of the peptides was tested on rabbits. All the peptides studied revealed humoral and cell response.

Benzo[h]naphthyridine N-oxides reacted with phenyl isocyanate in dimethylformamide to give carbamic acid derivative at room temperature or anilino derivatives at 150^oC. The process proceeded via 1,3-dipolar cycloaddition followed by aromatization with N-O bond cleavage and loss of CO₂ at higher temperature.

Toluenesulfonamidation of -pyronene (1,5,5,6-tetramethyl-1,3-cyclohexadiene) afforded two toluenesulfonamides:N,N'-(1',5',5',6'-tetramethyl-3'-cyclohexen-1',2'-diyl)di- toluenesulfonamide (9) and 4-methyl-N-(4',5',6',6'-tetramethyl-2',4'-cyclohexadien-1'—yl)benzenesulfonamide (12). Toluenesulfonamidation of ß-pyronene (1,2,6,6-tetramethyl-1,3-cyclohexadiene) gave N,N'-(3',4',5',5'-tetramethyl-3'-cyclohexen-1',2'-diyl) ditoluenesulfonamide (16). Allylic mono- and ditoluenesulfonamides 9, 12, 16 were reduced by sodium in liquid ammonia to corresponding allylic mono- and diamines 17,18 i 19.

The kinetics of oxidation of L-phenylalanine by alkaline permanganate follows the rate law -d[MnO₄^-]/dt   =  {k K[L-phenylalanine][MnO₄^- ]}/{1+K[L-phenylalanine]} where K is the formation constant for the complex between L-phenylalanine and permanganate and k is the decomposition rate constant. The data suggest that the oxidation of L-phenylalanine proceeds via the formation of a complex between L-phenylalanine and permanganate which decomposes slowly, followed by a fast reaction between the free radical of L-phenylalanine and another molecule of permanganate to give the products. The reaction constants involved in the mechanism are derived. There is a good agreement between the observed and calculated rate constants at varying conditions of experiments. The activation parameters are computed with respect to the slow step of the mechanism.

Nucleophilic vinylic substitution of 2,3,5,6-tetrachloro-1,4-benzoquinone by imidazole in acetonitrile and benzene has been studied spectrophotometrically. The reaction product is the diaminodichlorosubstituted quinone. The values of the activation parameters indicate that there is a considerable charge separation in the transition state. The reaction mechanism is discussed.

The effects of the substituent at position-2 and kind of the base on the rate of the base-catalyzed dimerization of 5(4H)-oxazolones have been investigated. The electron-donating and strong steric effect of the substituent at position-2 reduce markedly the proclivity of 5(4H)-oxazolones to dimerization. The following catalytic activity sequence of the bases has been found: DBU >> Et₃N >> (i-Pr)₂EtN.

The kinetics of oxidation of 8-hydroxyquinoline (oxine) by pyridinium dichromate has been studied in 60% acetic acid-water (v/v) medium. The reaction order is one with respect to oxidant, second with respect to the substrate and zero with respect to hydrogen ion concentration. Decrease of the dielectric constant of the medium, reduces the rate of the reaction. Increase in ionic strength has no effect on the reaction rate. The reaction does not induce the polymerization of acrylonitrile. From the kinetic data obtained, the activation parameters have been calculated and a plausible mechanism has been proposed.

Sound velocity in aqueous solutions of alkyltrimethylammonium bromides with alkyl chains of octyl, decyl, dodecyl and tetradecyl has been measured as a function of surfactant and NaBr concentrations at 25^oC. The critical micelle concentrations, CMC, were determined from intersections of two straight line portions of the surfactant concentration dependence of sound velocity in the solutions. CMC decreases with the increase of ionic strength, following the Corrin-Harkins equation. The standard free energy of micelle formation was estimated from the CMC at different NaBr concentrations. It was presented as a sum of increments of the methylene and the polar head groups at each NaBr concentration. The methylene group contribution varies with NaBr concentration from -1.81 kJ/mol in water to -2.95 kJ/mol at salt concentrations higher than 0.5 m NaBr.