The synthesis of racemic or enantiopure 2-diphenylphosphanyl-1,1'-binaphthalene-2'-thiol 8 (BINAPS) has been accomplished through a multistep reaction sequence from racemic or enantiopure binaphthol, respectively. The reaction sequence is completely stereoconservative. Enantiopure 8 can be alternatively obtained by resolution of rac-8 using the chiral benzylaminato Pd(II)-complex 16 as the resolving agent.

Selectivity has always been a major goal in any chemical processes, and particularly in organic synthesis. It is thus not surprising that more and more selective reagents have been developed in the last few decades. In photochemical reactions, the light can be considered as one of the reactants. Among the parameters characterizing the light, the wavelength is undoubtedly the most easily tunable one. This project aims at developing a set of functional groups that can be selectively activated by monochromatic light at various wavelengths, either to form bonds (eg. photoacylation) or to break bonds (eg. photodeprotection).

The kinetic of reaction between isocyanates and alcohols is determined in a great extent by the presence in the reaction system of substances able to inhibit or to activating reaction rate of urethane formation. The most important effect is produced by compounds that appear as reaction products (urethanes, urea). By using a HPLC (High Pressure Liquid Chromatography) method to follow the evolution of reaction composition in usual condition of urethane synthesis, as like amine actions, by introduce certain amounts of amide or urea in the reaction system, this catalysed reaction rate of urethane formation. The same effect the urethane addition present also, but in this case the urethane hydrogen atom presence is necessary.

The title compound was synthesised by the reduction of L-phenylalanine with lithium in liquid ammonia. Consistent with the Birch rule the main product was 2,5-dihydro-L-phenylalanine. 1,4-dihydro-L-phenylalanine was isolated by HPLC on a reversed phase column and characterised as a minor product of the Birch reduction. Both dihydro-L-phenylalanines were assayed in the phenylalanine ammonia-lyase (PAL) reaction. 2,5-Dihydro-L-phenylalanine was a substrate for PAL with Km about one third and Vmax 30 times less than that of the values of the natural substrate L-phenylalanine and converted into the corresponding 2,5-dihydrocinnamic acid. On the other hand 1,4-dihydro-L-phenylalanine was not converted by PAL. Both isomers were, however, competitive inhibitors of the enzymatic reaction. The Ki value of 1,4-dihydro-L-phenylalanine was 5.1 times higher as with the 2,5-dihydro isomer. These results support the proposed mechanism of the PAL reaction starting with an electrophilic attack of the 3,5-dihydro-5-methylidene-4H-imidazol-4-one (MIO) prosthetic group at the ortho position of the phenyl ring of the substrate.

An increasing number of isomeric (unnatural) nucleosides and nucleotides bearing an isomeric backbone, sugar or base have been characterized.1 A nucleobase isomer like isoguanine apparently makes feasible a non-standard base pair between 2`- deoxyisocytidine and 2`-deoxyisoguanosine when incorporated into oligomers. Some levels of functions by that isomeric replacement are retained and in some instances new functions are formed.2 The results reported by Switzer et al have shown that various polimerases handle this nonstandard base pair while Horn et al3 reported on the pairing in the absence of enzyme. Herein we report on a subtle change in a molecular shape by replacing N3-nitrogen with more lipophylic CH3-group and C8-H by N8-nitrogen.Though we do not prevent the Watson-Crick pairing the ring stacking might be altered. The absence of N3-nitrogen introduces an incorrectness that would disrupt the minor groove spin of hydration what means that should eliminate the presence of any ordered water molecules or metal ions at this sequence position.4 Recently,5 it has been demonstrated that in dA-dT sequences, the spine of hydration should be considered an integral part of the helix and the possible metal ions binding in the minor groove is critical for the structural integrity of duplex DNA.

The addition of dihalomethyl lithium reagents to ketones followed by assisted hydrolysis provides a- hydroxy aldehydes in good yield.

Cycloadditions between o-chloranil and norbornadiene produced a range of geometrical variants which were characterised as quinoxaline derivatives. Two ether products were also observed resulting from hetero Diels-Alder reactions. Photochemical irradiation of 20 produced the cage compound 22 as a result of an internal (2+2)p cycloaddition.

A three-component halo aldol reaction has been developed by using titanium tetrachloride as the halogen source as well as the Lewis acid mediator. The dehydration and elimination of hydrogen chloride were inhibited conducting the reaction at 0˚C in dichloromethane or at room temperature within a shortened period. Seven examples were examined to give good to high yields (61 - 92%) and modest stereoselectivity (syn/anti: 2.2/1.0 - 8.4/1.0).

The addition of cationic sulfenyl halides or other derivatives to double bonds is a well-known reaction [1]. The chemistry of b-heteroatom substituted organic sulfides, the products of these reactions has also been studied [2]. However, relatively little attention has been given to utilizing the addition process as a synthetic method. The work reported here was targeted at studying two potential synthetic applications of cationic arylsulfenyl species addition reactions; first, the preparation of chiral epoxides and, second, the enantioselective cationic cyclization, of polyene substrates. . Sulfenyl cations have previously been used by Livinghouse for cyclization processes but not in chiral fashion.

The research in the field of domino reactions is attracting considerable attention in synthetic organic chemistry since it enables the rapid assembly of complex molecules in one-pot processes.2 In this contest, very elegant examples have been reported in the literature dealing with palladium-catalyzed cascade processes where a single catalytic cycle entails several sequential bond transformations.3 On the other hand, the development of multistep palladium-catalyzed processes belonging to multiple sequential, but discrete, catalytic cycles, albeit synthetically interesting and mechanistically intriguing, has been so far virtually unexplored.