A number of new chiral ligands were synthesized starting from an accessible monoterpene, (+)-α-pinene. The new ligands were used in the vanadium-catalyzed oxidation of sulfides to chiral sufoxides. R 1 = R 3 = t-Bu, R 2 = H (a); R 1 = R 2 = R 3 = H (b); R 1 = 1,7,7-trimethylbicyclo[2.2.1]hept-2-yl, R 2 = H, R 3 = Me (c); R 1 = R 3 = CMe 2 Ph, R 2 = H (d); R 1 = R 2 = H, R 3 = NO 2 (e); R 1 = R 3 = NO 2 , R 2 = H (f); R 1 = R 2 = H, R 3 = OMe (g); R 1 = OMe, R 2 = R 3 = H (h); R 1 = R 3 = H, R 2 = NEt 2 (i); R 1 = Br, R 2 = H, R 3 = NO 2 (j).Optically active monoterpenes and their derivatives are widely used as source of chirality in asymmetric synthesis [1]. In the recent time, application of ligands derived from monoterpenes in asymmetric oxidation of prochiral sulfides to optically active sulfoxides has been reported [2-6]. Chiral sulfoxides play an important role in asymmetric synthesis [7,8], and many of these compounds exhibit strong biological activity [9].We recently synthesized a large series of new chiral Schiff bases Ia-Ij on the basis of an accessible monoterpene, α-pinene [3]. These compounds were used as ligands in vanadium-catalyzed asymmetric oxidation of sulfides. It was found that the largest enantiomeric excess (ee) in the oxidation of thioanisole (II) to sulfoxide III was attained in the presence of ligand Ia (ee 32%) [3] (Scheme 1). In the oxidation of sulfide V as precursor of effective antiulcer drug Esomeprazole (VI), the most efficient was ligand Ib (ee up to 31%)[4]. Hydrogenation of Schiff bases derived from chiral α-diamines and substituted salicylaldehydes gave the corresponding amines which were used as ligands in asymmetric oxidation of thioanisole (II). As a result, enantiomeric excess was raised to 95% (in the presence of initial Schiff bases enantiomeric excess did not exceed 20%) [10]. Although these data were not reproduced (the largest enantiomeric excess of sulfoxide III was 26% [11]), it is obvious that replacement of Schiff bases by the corresponding amines should affect the yield and enantioselectivity of the above transformations to an appreciable extent.The goal of the present work was to synthesize new chiral amines from Schiff bases derived from α-pinene, and estimate their potential as ligands in vanadiumcatalyzed asymmetric oxidation of sulfides. In addition to ligands Ia-Ij synthesized previously, by reaction of amino alcohol (-)-VII with 3-tert-butyl-2-hydroxy-5-(2-methoxyethyl)benzaldehyde (VIII) we obtained in quantitative yield new Schiff base Ik having a methoxyethyl group in the para position with respect to the phenolic hydroxy group (Scheme 2).By slow evaporation of a solution of compound Ia in chloroform we succeeded in obtaining for the first time single crystals of the corresponding hydrate, and the molecular and crystalline structure of Schiff base Ia was studied by X-ray analysis (Fig. 1). The hydroxyphenylmethylidene fragment C 3 N 1 C 12-18 is planar within ± 0.059 Å. The C 4 atom in the pinane fragment deviates from the C 2 C 3 C 5 C 6 plane by 0.180(...

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Experiments on rats showed that n-tyrosol limited the increase in blood viscosity during thermal exposure at a shear rate of 5-300 sec(-1) and inhibited ADP-induced platelet aggregation. The effects of n-tyrosol are comparable to that of pentoxyphylline.

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