Marco Boccalini

Natural and synthetic geiparvarins are strong and selective MAO-B inhibitors. Synthesis and SAR studies.

Natural geiparvarin 1 and a number of its analogues were prepared and tested as inhibitors of both monoamine oxidase isoforms, MAO-B and MAO-A. The desmethyl congener 6 of geiparvarin, proved potent and selective MAO-B inhibitor (pIC(50)=7.55 vs 4.62). X-ray crystallography and molecular modelling studies helped the understanding of the observed structure-activity relationships.

New geiparvarin analogues from 7-(2-oxoethoxy)coumarins as efficient in vitro antitumoral agents

A new class of compounds analogues of geiparvarin is described: aldolic condensation of 3(2H)-furanones and 7-(2-oxoethoxy)coumarins followed by a very efficient dehydration protocol led to the title compounds which show good antitumoral activity against several human cell lines.

New 5-(2-ethenylsubstituted)-3(2H)-furanones with in vitro antiproliferative activity

Abstract A convenient route to new 3(2H)-furanones is described through hydrogenolysis and subsequent acidic hydrolysis of isoxazoles. The antiproliferative activity of title compounds were evaluated against leukemia-, carcinoma-, neuroblastoma-, and sarcoma-derived human cell lines in comparison to the natural compound geiparvarin. The structure activity relationship indicated that the maximum in vitro antiproliferative activity correlates with the presence of a heterocyclic ring on the ethenyl moiety.

A new convenient route to 2-oxoethoxycoumarins: key intermediates in the synthesis of natural products

A new synthetic route to coumarinyloxyaldehydes starting from hydroxycoumarins is presented; these compounds, useful intermediates in the preparation of natural products such as geiparvarin and psoralens, are now available in excellent yields with a simple workup procedure. Moreover the reported route has been applied to dihydroxycoumarins.

A convenient synthesis of psoralens

An efficient synthesis (yields >70%) of linear 7H-furo[3,2-g]chromen-7-one derivatives (psoralens or furocoumarins) has been carried out starting from ring-substituted 2-(coumarin-7-yl)oxyaldehydes; moreover, the phototoxicity of these compounds has been tested on a cultured cell line of murine fibroblast.

GIAO DFT 13C/15N chemical shifts in regioisomeric structure determination of fused pyrazoles.

The combined use of two‐dimensional NMR correlation experiments and gauge including atomic orbital density functional theory in 13C NMR chemical shift (CS) calculations allowed reliable and simple structural determination of regioisomeric heterocyclic systems that originate from the reactions of acylquinolinones with substituted hydrazines. Moreover, the results of differential analysis between the calculated 15N NMR CSs for hypothetical structures and the experimental data of the title azaheterocyclic systems were even more advantageous with respect to 13C because there was no need for correlational analysis: structures of the regioisomeric compounds could be determined just by direct comparison. Copyright

Synthesis and Biological Evaluation of New Geiparvarin Derivatives

New geiparvarin derivatives modified at the alkenyloxy bridge, where the 3′‐methyl group was replaced by a hydrogen atom, were synthesized and evaluated against a panel of human tumor cell lines in vitro. Compounds (R)‐4 and (R)‐5 show greater inhibitory activity toward cell growth than the parent geiparvarin.

Regio- and stereoselective reductions of dehydrocholic acid

Dehydrocholic acid (DHCA), an unnatural bile acid, is manufactured by oxidation of cholic acid. Its biotransformation by two basidiomycetes (Trametes hirsuta and Collybia velutipes) is reported. These mycelia showed different affinities for the substrate and selectivities of attack: T. hirsuta in particular regio- and stereoselectively reduced the 3-keto group to yield 3 alpha-hydroxy-7,12-diketo-5 beta-cholan-24-oic acid (7,12-diketolithocolic acid) as the main product. A number of different chemical reductions were carried out on DHCA; among them hydrogenation with Raney Nickel in water under high-intensity ultrasound proved highly regio- and stereoselective, yielding 7,12-diketolithocolic acid exclusively. (1)H and (13)C resonances were assigned in details thanks to a series of 1D and 2D NMR runs including DEPT, NOESY, H-H COSY, gHSQC and gHMBC.

Microwave-assisted reaction of glycosylamine with aspartic acid

The synthesis of N-protected glycosyl amino acids from amines has been investigated and it was found that, under microwave conditions, glycosylamines could be hydrolyzed leading to new products containing a glycosyl ester linkage. The efficiency of the microwave-induced glycosylation of aspartic acid was studied comparing the microwave activity between amide and ester bond formation. Different sugar moieties have been employed to demonstrate the simple and reproducible coupling methodology. New glycosyl ester compounds were further characterized by NMR spectroscopy.