In a preceding paper we have reported the stereoselective synthesis of a b-lactam tricyclic structure exploiting the chirality induced by ortho substituted chromiumarenes as well as its activation to the nucleophylic aromatic substitution, according the following Scheme:

A new and efficient synthetic route to malonamides and malonamic acid esters is described. S-tert-Butyl acetothioacetate monoanion reacted with aryl or alkyl isocyanates to give tricarbonyl compounds, which spontaneously deacetylated to the corresponding b-amidothioesters. Treatment of the latter with aliphatic or aromatic amines or alcohols at room temperature in the presence of silver trifluoroacetate provided malonamides or malonamic acid esters, respectively, in excellent overall yields.

As part of a programme to evaluate the imidazolinium ylides 2 in 1,3-dipolar cycloaddition reactions [1], we wished to explore intramolecular cycloaddition. The azomethine ylides 2 are prepared (Scheme 1) by alkylation of imidazolines 1 with an active halide such as an a-halo ester (X = CO2R) and addition of a base (DBU); in the presence of a dipolarophile, the dipole 2 undergoes regioselective and diasteroselective cycloaddition (e.g. Scheme 1). Thus in onepot, three of the five bonds of a new pyrrolidine ring are assembled

Dried manganese dioxide (MnO2), potassium permanganate (KMnO4) and barium manganate (BaMnO4) in the presence of anhydrous aluminum and ferric chlorides performed efficient deprotection of S,S- acetals , 1,3-dithiolanes and 1,3-dithianes, in dry CH3CN at room temperature. Thioacetals derived from enolizable carbonyl compounds remained almost intact.

The fullerene-82 cavity is selected as a model system in order to test several methods for characterizing inclusion molecules. The methods are based on different technical foundations such as a square and triangular tessellation of the molecular surface, spherical tessellation of the molecular surface, numerical integration of the atomic volumes and surfaces, triangular tessellation of the molecular surface, and a cubic lattice approach the molecular volume. Accurate measures of the molecular volume and surface area have been performed with the pseudorandom Monte Carlo (MCVS) and uniform Monte Carlo (UMCVS) methods. These calculations serve as a reference for the rest of the methods. The SURMO2 method does not recognize the cavity and may not be convenient for intercalation compounds. The programs that detect the cavities never exceed 1-% deviation relative to the reference value for molecular volume and 5% for surface area. The GEPOL algorithm, alone or combined with TOPO, shows results in good agreement with those of the UMCVS reference. The uniform random number generator provides the fastest convergence for UMCVS and a correct estimate of the standard deviations. The effect of the internal cavity on the solvent-accessible surfaces has been calculated. Fullerene-82 is compared with fullerene-60 and -70.

Quantum mechanical calculations were carried out to study the molecular geometry and electronic structure of 2-amino-2-desoxigliukopyranose (AG) and N-acetyl-, N-ethanoyl-, series of N-phthalimidealkanoyl-AG . The total charge density, electrostatic potential, spatial distribution and positions of HOMO and LUMO of N-acyl-AGs with respect to their substitutes yield information on the reactivity of the molecules.

Continuing our investigations (poster1, 2) concerning the irreversible inhibition of serine-hydrolases (acetylcholinesterase, chymotrypsin) by organophosphates [1][2] we have prepared the racemic 3-fluoro-2,4-dioxa-3l5-phosphabicyclo[4.4.0]decan-3-ones (±)-7-(±)-12. Being conformationally restricted, these cis- and trans-decalinetype congeners with the F-substituent in the axial and equatorial position fit differently into the active site of acetylcholinesterase (AChE) as represented by their kass-values.

The influence of the anomeric effect on bicyclic organophosphates could be shown for the first time by means of X-ray analysis. In the course of our syntheses of bicyclic organophosphates as inhibitors of acetylcholinesterase we have been able to crystallize a series of four isomeric compounds: (±)-7-aza-7-benzyl-3-fluoro-2,4-dioxa-3l5- phosphabicyclo[4.4.0]decan-3-ones (±)-1ax,eq and (±)-2ax,eq, cis- and trans-decaline-type congeners with the Fsubstituent in the axial and equatorial position. The syntheses of the mentioned and of some related compounds as well as their inhibitory effects on acetylcholinesterase are described on a separate Poster A0047

a,b-Diketoesters can be conveniently prepared from the corresponding a,a’-dioxo-type oximes or oxime ethers using a zinc/AcOH reduction system.

In recent years there has been increasing interest in the design of alkyl 1,4-dihydropyrimidine-5-carboxylates (1,4-DHPMs) and related Biginelli-like compounds [1] which are presented as valuable substitutes [2] for the well known Nifedipine® and other 1,4-dihydropyridine drugs [3] clinically used in the treatment of cardiovascular diseases. That interest is illustrated, i.a., by the disclosure of elegant protocols involving solid phase synthesis approaches [4] as well as solvent-free preparations under microwave irradiation. [5] The purpose of the present work is to extend the scope of those studies to 2-amino derivatives and especially to the evaluation of their synthetic potential for the construction of novel pyrimido[1,2-a]pyrimidines, a ring system that can be found in marine-derived natural products such as crambescidin [6] and batzelladine [7] alkaloids.