The synthesis of new multichiral center monophosphine ligands 1-3 was achieved and assessed in the enantioselective palladium catalyzed allylic substitution of 1,3-diphenyl-2-propenyl acetate 4 with enantioselectivities up to 92%

1,2-Amino alcohols are important and versatile synthetic intermediates for the preparation of a wide variety of natural products, drugs, and metal-binding ligands [1]. Consequently the development of synthetic methods for their preparation in a stereocontrolled manner has received significant attention for quite some time. In general, the hydroxyl group of the amino alcohol is installed either by the addition of an organometallic reagent to an aminocarbonyl compound 1 or by the reduction of an amino ketone 1 (R2 not H) (Scheme 1) [2]. Moreover stereochemical control is good for either strategy when the amino group is a primary, secondary, or tertiary amine 1 (P, P'= alkyl, H), which is the most common class of amine used in these reactions.

The total synthesis of natural products requires selective methods to adapt to the structural complexity the nature has introduced in natural compounds. From this challenge derives the impetus to find new reactions, new reagents and new catalysts to run reactions in a chemoselective, regioselective and stereoselective way. Recently, domino or multicomponent,1 combinatorial2 or enzymatic3 processes, have expanded the synthetic tools available to researchers, and topics like atom economy4 and environmentally friendly syntheses became the concern of organic chemists. Having in mind all these points we approached the synthesis of natural products like glycosidase inhibitors,7 belonging to the classes of indolizine5 and pyrrolizine6 alkaloids, which are attracting growing interest from synthetic chemists for their various and essential biological activities

Cross-conjugated mesomeric betaines play an important role in heterocyclic synthesis. They can act as 1,4-dipoles in cycloaddition reactions or can be rearranged at higher temperatures to thermodynamically more stable compounds [2,3,4]. The rearrangement of cross-conjugated mesomeric pyrimidines has been extensively studied. When substituted on nitrogen with an aryl substitutent they can be rearranged to 2,3-disubstited 4-quinolones via unsaturated ?-lactame intermediates [2,3,5] (type A rearrangements [3])or via 2-oxoketenes to 4-hydroxy-2-quinolones (type B rearrangements [2]) [2,3,4,6]. In this paper we want to present type B rearrangements of pyridazino[2,3- a]pyrimidines in which the intermediate 2-oxoketene has two possibilities for ringclosure reactions to lead to thermodynamically more stable compounds. The thermolysis of pyrido[1,2-a]pyrimidines has been described before [6]. For this investigation two typs of pyridazino[2,3-a]pyrimidines were required. One with (the usual) electron-deficient pyridazine moiety (4) and one with with an electron rich pyridazine nucleus (7), i.e. with a high electron density at position 9 to allow an electrophilic attack of the expected ketene intermediate.

Azidohetarenes have found large interest because of its reactive azido group which gives a number of reactions which can be used synthetically [1]. We have prepared previously a number of hetaryl azides [2] having reactive substituents such as phenyl-, acyl-, hydrazono- and nitro groups in ortho-position which were used as synthons for thermolytic induced heteroelectrocyclic ring closure reactions. In this contribution we studied the thermal behavior of azidoarenes and azidohetarenes with and without reactive ortho-substituents to get insights in the thermal properties of these compounds which are interesting and important for thermal reactions.

The combination of an indium complex with lithium perchlorate affords a potent system for the catalytic acylation of electron-rich aromatics

Ab initio and DFT quantum chemical calculations have been applied to a study of Diels-Alder reactions of o-benzoquinone as diene and norbornadiene as dienophile. Transition states for these reactions are located and activation energies estimated. The prefered exo-¶- facial selectivities and exo,endo- stereospecificities exhibited in these cycloadditions are readily predicted using RHF/3-21G or higher levels of calculations. Differences between experimentally observed results and calculations may be explained by the postulation of a second, nonconcerted biradical mechanism leading to formation of hetero Diels-Alder products.

Acridines are a well kown group of compounds [1] with a wide variety of biological properties [2]: DNA intercalating agents, anticarcinogenic, bactericidal, antimalarial, insecticides and antifungic. There are several aproaches to their synthesis. Bernthsen reaction is one of the classical methods. It is mainly the heating of diphenylamine in the presence of zinc chloride and a carboxylic acid, temperature of reaction is 200-210ºC and reaction times are several hours. But usually the yield are low. In our group we are interested in the application of microwave heating to organic synthesis [3], usually this reactions employ a domestic microwave oven and reaction vessels are just test tubes or beakers opened to the air. Bernthsen reaction seemed to be an ideal candidate to substitute conventional heating by microwave heating.

Our group has been investigating on the transformation of styrene derivatives into ß-phenylethylamines [1]. We had previously worked on the carbolithiation of styrenic compounds and we achieved successfully the hydroxylation of the -position of styrene [2]. However this method proved to be unsuccessful when applied to addition of lithium amides

In the last years we have been searching on the reactivity of styrenic compounds towards nucleophiles [1], in this communication we want to report he reactivity of beta-methoxystyrene towards butillithium and lithium amides. The addition of alkyllithiums and lithium amides to styrene usually is followed by the addition of an electrophilicreagent that quenches the benzylic anion.