Naturally-occuring cinchona alkaloids were exploited in two different approaches for enantioselective fluorination. Firstly, the phase transfer catalysis involving cinchona-alkaloid-derived quaternary ammonium salts was investigated. Poor results were obtained (7% ee, 60% yield) in the fluorination of N-phthaloylphenylglycine ethyl ester. In an alternative method we describe the first ever enantiopure N-fluoro quaternary ammonium salts of cinchona alkaloids as enantioselective fluorinating agents. A one step transfer-fluorination on the alkaloids gave the [N-F]+ reagents. This new generation of fluorinating agents exhibit asymmetric induction ranging from 56 to 92% ee in the fluorination of enolates and silyl enol ethers.

The usual way of commercial 4-aminopyridine preparation is a two-stage synthesis starting from pyridine and including 1-(4-pyridyl)pyridinium chloride hydrochloride as an intermediate. The total yield is 36- 40% [1, 2, 3]. A semipreparative scale three-stage synthesis including pyridine-N-oxide and 4-nitropyridine-N-oxide as an intermediates is preferable. At the third stage 4-nitro-pyridine-N-oxide was reduced with iron and acetic acid at reflux temperature to produce 4-aminopyridine in quantitative yield. The reaction demands continuous extraction with diethyl ether of the title compound. The total yield is 65% [4].

Triarylamine-N-oxides are mainly of interest to theoretical organic chemists. The first mention of triphenylamine-N-oxide (I) [1] was an erroneous one. In fact, in the original paper [2] I has not been described. In reference [3] the acetone solution of the I : UO2Cl2 1:1 complex was described without any experimental data for the above mentioned complex or for the ligand preparation. Up to the present time no synthetic procedure for triarylamine-N-oxide preparation were described. Their stability seems tobe much lower than the stability of other known amine-N-oxides. In our opinion, (4,4¢,4¢¢-trimethyl)- triphenylamine (II) forms a relatively stable (4,4¢,4¢¢-trimethyl)-triphenylamine-N-oxide (III).

Silyl ethers are well established protective groups in organic synthesis [1]. They are easily prepared and cleaved, and their reactivity can readily be controlled by the appropriate choice of the groups attached to silicon. In the course of our ongoing investigation of the chiral (tert-butyl)(methyl)(benzyloxymethyl)silyl group (I) as an auxiliary to control stereoselective processes [2] we got interested in the combined use of I as a protective and stereochemically directing group.

Phosphorus containing compounds have gained considerable attention due to their diverse biological and chemical profiles. A number of P-heterocycles have shown potent biological activity, and have become attractive targets as rationally designed small molecules. We are interested in continuing to build a library of highly functionalized heterocyclic phosphorus-containing compounds of varied chemical and biological interests. In out pursuit of novel P-heterocycles, we have recently become interested in the synthesis of amino acid-based phosphorus containing compounds that may have potentials as HIV-1 protease-inhibitors. Our efforts have largely been driven by the development of a number of cyclic urea-based HIV-1 protease inhibitors at Dupont-Merck that gave promising biological activity.

R-(+)-2-Methylbutanol 10a, a building block of several natural products, is commercially unavailable. The total synthesis of 10a in four steps utilising the boronic ester homologation approach is described.

The transfer of oxygen atoms plays an important role in organic chemistry. Carbonyl oxides 1 and the isomer dioxiranes 2 are discussed as short-lived intermediates in decomposition processes, oxidations of organic compounds (Baeyer-Villiger Reaction, Ozonolysis), and enzymatic processes 1, 2, 3. During the last years 2 have have been used as selective oxygen transfer reagents 4, 5, 6, 7, 8, 9. A successful technique for the stabilization of reactive molecules is the introduction of sterically demanding groups such as t-butyl or mesityl. While several derivatives of dioxiranes 2 could be synthesized and characterized in solution, carbonyl oxides 1 are in general transient spezies.

2,4-Dihalo-8-methylquinolines 2,3 have been prepared and subjected to azidation and hydrazination reactions showing interesting regioselective properties to give compounds 4-10. The targeted aminoquiolines 13, 14, 15, 17, 19, 22 and 23 were obtained via hydrolysis of their corresponding phosphazenes 11, 12, 16, 18, 20 and 21, respectively. These phosphazenes have been preliminary obtained by condensation of azido and/or tetrazoloquinolines 4, 5, 6, 10, 18 and 22, with triphenylphosphine in either boiling benzene or 1,2-dichlorobenzene.

A detailed investigation into the influence of phosphines, additives, bases, and solvents on the Heck coupling reaction of 4-trifluoromethyl-1-chlorobenzene (2) is presented. It is shown that a number of catalyst systems exist for efficient cross coupling of electron deficient aryl chlorides with various olefins. Basicity and steric demand of the ligand are two factors which determine the success of the reaction. In addition the phosphine / palladium ratio, the correct type and amount of additive, and finally the use of an appropriate base and solvent are also important. The optimised reaction conditions are applied for the arylation of styrene, butyl vinyl ether, and N,N-dimethyl acrylic amide with various aryl chlorides.

A number of thiophene-S-oxides were prepared from the corresponding thiophenes. Their reactivity upon photoirradiation was studied.[1] It was found that the photoreactivity of the thiophene-Soxides depends greatly on their substitution pattern.