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Hydrocynation of cyclic α-sulfinyl ketones under different conditions has been studied. The obtained results show that compounds derived from cyclohexanone react with Et2AlCN yielding only sulfinyl cyanohydrins exhibiting different configurations at sulfur and at hydroxylic carbon. The stereoselectivity is lightly lower but also very high starting from α-sulfinyl cyclopentanones. The influence of Lewis acids as well as the stereochemical course of these reactions have also been discussed.

The reaction of molecular oxygen with several 2,4-disubstituted oxazolones (3a-3g) is studied in the present paper. It is shown that oxygen may induce oxidative dimerization to dehydrodimers (7a-7g) via the mesoionic form of the oxazolone. The equilibriation between the ketonic and the mesoionic forms. It is demonstrated that this equilibrium and the dimerization process are dependent on the properties of the solvent and the type of substitution in the oxazolones.

The hydride reductions of chiral N-(2-p-tolylsulfinyl)cyclohexylidene phenyl amines 3A and 3B (epimers at C-2), and of N-1-(2-p-tolylsulfinyl)cyclohexenyl benzyl amine, 4, are highly stereoselective, yielding only the corresponding cis-aminosulfoxides.

The conformational study of the title compounds is reported. The configurational assignment of the epimeric sulfoxides was based on the relationship between the stereochemistry of the sulfinyl group and the chemical shifts of the neighboring nuclei. The values of the (Z/Y) gaucha interactions have been estimated in different solvents from G0 values measured in low temperature 13C-nmr spectra.

The synthesis and conformational analysis of 2-fluoro, 2-hydroxy and 2-methoxy thioderivatives (thioethers, sulphoxides, sulphones and sulphonium salts) of 1,2-dimethyl and 1,2-diphenylethanes ( erythro and threo ) are reported. Steric effects in thioethers and electrostatic interactions in sulphonium salts are the main factors determining the stability rotamers. A balance of these factors controls the conformational equilibria in sulphoxides and sulphones. Electronic interactions between the π -aromatic electrons or the unshared β-heteroatomic electrons and the sulphur atom are suggested to explain large differences in rotamer populations induced by changes in the carbon sketelon or in the relative configuration of the sulphinylic sulphur.

The synthesis is given of oxisuran (methylsulphinyl methyl-2-pyridyl ketone) and its metabolites and derivatives, whose structures are 2-Py-CO-CH2-SOxCH3 ( X=0,1,2) and 2-Py-CHOR-CH2-SOnCH3(R=H, Me; n=0,1,2). From the results obtained in the reaction of oxisuran with different reducing agents, a new stereochemical pathway is suggested to explain the stereoselectivity observed in the reduction of β-keto-sulphoxides with DIBAL. The conformational analysis of hydroxy and methoxyderivatives is discussed in relation with that previously reported for 2-thioderivatives of 1-phenylethanol and their O-methylderivatives. The configurational assignment of diastereoisomeric sulphoxides is made on the basis of their different conformational behaviour, confirming the assignment deduced from the stereoselectivity observed in the reduction of oxisuran.

From the results obtained in the hydrolysis reaction of the carbamate group of some thioderivatives compounds whose common structure is (2 → tOOCNH-C6H4)-CHOH-CH2Y a mechanism is suggested to explain the products, as well as the relationship between the relative configuration of diastereoisomeric sulfoxides (Y = SOMe) with the reaction rate and with the stereochemical outcome. Other interesting and unexpected products are yielded when the hydrolysis reaction of others carbamates (Y = H, Br, CN) is carried out In the present cases, the carbamate functioh seems to behave as a very versatile group capable of readily undergoing conversions to several Kinds of heterocycles.

The reaction of Δ 2 -oxazolin-5-ones 1a and 1b with nickel peroxide in benzene produces the corresponding 4,4-dehydrodimers 5a and 5b as the main products in yields over 75%. Under the same conditions, the 2-aryl -4-methyl - Δ 2 -oxazolin-5-ones 1c , 1d and 1e yield five products. In the case of 1c , the constituents of the product mixture were separated and identified as two 4,4-dehydrodimers ( meso and d] pair isomers) 5c and 5c ', (40.7%), 2,4-dehydrodimer 6c (34.9%), acetylanisoylimide 8c (8.5%) and anisamide (15.9%). Adequate mechanistic schemes are discussed to account for the products formed.

The synthesis, isolation and conformational analysis of the diastereomeric 2-methylsulphinyl-1,2-diphenylethanol and of its O -methyl and O -acetyl derivatives are reported. Chemical correlations and the study of the influence of solvent polarity changes on the coupling constants have permitted the configurational assignment. Lanthanide shift reagents have been used also. to this effect. The role of hydrogen bonding in the hydroxysulphoxides has been evaluated in diluted solutions by IR and NMR spectroscopy. A donor-acceptor interaction between oxygen and sulphur has been invoked to explain the differences in conformational behaviour between epimeric sulphoxides at sulphur atom.

Synthesis of cis- and trans-N-methoxycarbonyl-2, 3-dimethyl-l, 4-thiamorpholine and their S-oxides and S, S-dioxides by intramolecular reaction of the corresponding 2-methoxy-carbonylaBinoalkyl-2' -chloroethyl thioethers, sulfoxides and sulfones with sodium hydride in dimethylformamide at room temperature is reported. Cyclization of chlorothioethers and -sulfones is Stereospecific although, in the case of sulfones, the formed 1, 4-thiamorpholines S, S-dioxides epimerize at C(2) after long reaction times. In chlorosulfoxides, elimination of HCl is previous to cyclization which also resulted stereospecific except in the case of the acyclic starting material of R*s,S*1,S*2 configuration, where epimerization at sulfur takes place.

2,4-diphenyl- and 2-p-methylphenyl-4-phenyl-Δ2-oxazolin-5-ones react at 80–110°C with nitrosobenzene to give benzamidines. However, reactions conducted at room temperature afford in high yield, the heretofore undescribed Δ4-1,2,4-oxadiazolin-3-carboxylic acids by regiospecific 1,3-dipolar cycloaddition. Thermal decomposition of the oxadiazolinecarboxylic acids gives the corresponding benzamidines.

Δ4-1,2,4-Oxadiazolin-3-carboxylic acids, 3a_3i, were obtained by 1,3-d i polar cycloaddition between Δ2-oxazolin-5-ones, 1 , and nitrosobenzene, 2. The reaction occurs regiospecifically at room temperature, the mesoionic form of 1 acting as the 1,3-dipole and the N=O group of 2 acting as the dipolarophile. Xylene or DMF are used as solvents. The thermally unstable aminoacids were converted into their methyl esters, 4a–41 , by treatment with diazomethane. The esters were characterized by their physical properties.

The kinetic behaviour of the acetic acid-catalysed reaction of 2-phenyl-4,4-dimethyl-2-oxazolin-5-one (1) with the ethyl esters of glycine (2), dl -α-aminobutyric acid (4), α-aminoisobutyric acid (5), dl -norvaline (6), dl -valine (7), dl -leucine (8) and dl -phenylalanine (9) has been investigated. Within the concentration ranges employed the reactions follow second order kinetics, with no dependence of the experimental rate constant on the initial concentration of 1, just as found previously for the ethyl ester of dl -alanine. To explain the function of the catalyst a cyclic intermediate has been compared with other intermediates proposed for similar reactions. A good correlation has been obtained between the rate constant for the catalysed reaction and Taft's σ* values, showing that the effects of the substituents on the esters are mainly polar and supporting the structure of the proposed intermediate.

The kinetic behaviour of the acetic acid catalysed reaction of 2-phenyl-4,4-dimethyl-2-oxazolin-5-one (1) with the ethyl ester of DL -alanine (2) in CCl4, to give the ethyl ester of N-(N′-benzoyl-α-amino-isobutyryl)- DL -alanine (3) is investigated. Within the range of concentrations employed, the reaction follows the rate equation ν = ko + k[monomer] [oxa] [ester], where ko is the specific rate constant of the uncatalysed reaction, and k′ is that of the catalysed reaction. The influence of the variation of 1, 2 and acetic acid on the specific rate constant is studied. It is shown that only if the acetic acid monomer is regarded as the catalyst can the system be adequately described quantitatively. The participation of other acid species as catalysts is discussed.

The dimerization constant, K1 of acetic acid in CCl4 is determined by an IR spectrometric method and is found to have a value of 2252M−1 at 20°. The association constants, K2, for the interaction between the acetic acid monomer and some aminoacid ethyl esters are determined by the same method and found to have the values given (in M−1 at 20°) for the esters of the following aminoacids: glycine (282 ± 24), dl -alanine (236 ± 33), dl -α-aminobutyric acid (139 ± 11), α-aminoisobutyric acid (172 ± 18). dl -norvaline (104 ± 13), dl -valine (150 ± 8), dl -leucine (108 ± 18) and 3-phenyl- dl -alanine (140 ± 21). A correlation of these experimental values with some structural parameters related to the steric effect of the substituents on the esters is proposed.