Pyrido[2,3-d]pyrimidine systems A are of chemical and chemotherapeutical interest because they show both the properties of a 4-hydroxy-2-pyridone (present in a series of natural products and biologically active structures, e.g. [1]) and of uracil in one ring system.

Eight thia- or azasubstituted butyric acid derivatives was prepared and influence of this substituent onto carbon atoms of benzene ring was studied

a-Hydroxy ketones including their cyclic derivatives are important synthetic building blocks. Chiral, non-racemic a-hydroxy ketones (and esters) are widespread in natural products. Therefore, there is a high demand to develop efficient methods for the construction of their enantiopure or at least enantiomerically enriched representatives and a number of procedures have been published in the last decades [1,2]. Our interest in the synthesis of a-hydroxy benzo(hetera)cyclanones, particularly 3-hydroxychromanones, prompted us to investigate the synthetic utility of the recently developed electrophilic chiral oxidizing system, namely dimethyldioxirane (DMD)/Jacobsen's catalyst [3] in the oxyfunctionalization of enol derivatives. Enol acetates were choosen as prochiral substrates because their higher stability as compared to silyl enol ethers and their high reactivity toward DMD

Until recently the most publications on furylarylmethanes were devoted to their application as promising source for polymer producing [1-3] or as intermediates in the synthesis of calixarenes and crown ethers [4, 5]. At the same time, due to the availability of furan ring in the molecules of these compounds they can serve as convenient and useful precursors for syntheses of various heterocyclic compounds condensed with benzene cycle. But looking through the literature we could find only one example of similar use of furylarylmethanes: Prof. Gurnos Jones and co-workers obtained carbazole derivative from 2-nitrophenyldifurylmethane under treatment of latter with triethylphosphite

Although at last time the most of investigators put their attention to development of convenient approaches to synthesis of asymmetric furylhetarylalkanes, symmetric di- and trifurylmethanes keep their importance as before. Some derivatives of difurylalkanes use in various fields of industry. Our stydies let us to elaborate convenient routes to several derivatives of symmetric di- and trifurylmethanes series.

Preparation of a,a -disubstituted glycines is a matter of current interest owing to their importance as enzyme inhibitors and peptide modifiers. Herein, we describe a new simple methodology to prepare enantiopure a,a -dialkylglycines based on the use of commercially available D-ribonolactone as chiral auxiliary. Enantiopure a -methyl and a -butyl series are prepared through diastereoselective alkylation and posterior Schmidt rearrangement of a,a -dialkylacetoacetates of D-ribonolactone acetonide. Absolute configuration was assigned through preparation of enantiopure 4,4-disubstituted 3-methyl-2-pyrazolin-5-ones

While abundant information on the reactivity of several classes of nitrones exists [1], hetaryl nitrones, i.e. nitrones bearing an heterocyclic ring at the carbon atom, have been the subject of very few investigations [2]. Recent publications from our laboratory have been concerned with the use of thiazolyl nitrones 1 as a suitable substrate for both nucleophilic additions [3] and 1,3-dipolar cycloadditions [4]. Our continued interest in the reactivity of hetaryl nitrones has led to investigate the reaction of the furfuryl nitrones 2 with several alkenes. In this communication we report our preliminary results on this topic.

The preparation of several disulfonamides 3 and 4 derived from camphor are described, as well as their use in the titanium tetraisopropoxide-promoted enantioselective addition of diethylzinc to benzaldehyde, the enantiomeric ratio being up to 82.0:18.0.

Anions of heterocyclic five-or six-membered 1,3-dicarbonyl systems react with aromatic disulfides and other -S-S- systems, such as dithiuramdisulfides in DMF in the presence of potsssium carbonate to yield sulfides. The heterocyclic systems studied include pyrazol-1,3-diones, barbituric acid [1], 6-hydroxy-3(2H)-pyridazinones [2], 4-hydroxy-2-pyrones, 4-hydroxy-2-pyridones, and their benzo derivates (e.g. coumarins and 2-quinolones [3]). Oxidation of the aromatic sulfides with peracids yields sulfones, while careful oxidation with hydrogenperoxide in alkaline medium affords the sulfoxides. The latter class of compounds are heteroanalogs of the well known cyclic tricarbonyl methane derivatives (SO instead of CO) which show a broad range of biological activity, especially in agricultural chemistry.

Over the past years chiral cyanohydrins (a-hydroxynitriles) have become a versatile source for a variety of chiral building blocks. Several classes have already been synthesized, including b-hydroxy-a-amino acids [1], a-hydroxy-b-amino acids [2], a-hydroxy ketones [3] and b-hydroxy nitrones [4]. Although chiral a-hydroxy aldehydes are interesting compounds, their synthesis from chiral cyanohydrins has always been difficult. Some examples of the synthesis of chiral a-hydroxy aldehydes have been published but the results, both in yield and optical purity, seem to be contradictory [5]. This poster describes the first results of the synthesis of O-protected chiral a-hydroxy aldehydes and their subsequent use in the Horner-Wittig reaction.