Iodine-Catalyzed Iso-Nazarov Cyclization of Conjugated Dienals for the Synthesis of 2-Cyclopentenones.

Molecular iodine was identified as an efficient catalyst for the cycloisomerization of conjugated dienals to substituted 2-cyclopentenones. DFT calculations suggested an unexpected concerted character for this cyclization.

Activity of the pterophyllins 2 and 4 against postharvest fruit pathogenic fungi. Comparison with a synthetic analog and related intermediates.

The antifungal activity of pterophyllin 2, pterophyllin 4, a 5-desmethyl analog of the latter and some of their synthetic intermediates, against three postharvest phytopathogenic fungi, was evaluated. The target fungi were Rhizopus stolonifer, Botrytis cinerea and Monilinia fructicola, which affect fruits worldwide, causing important economic losses. The tests were carried out with imazalil and carbendazim as positive controls.

Total syntheses of gerberinol I and the pterophyllins 2 and 4 using the Casnati-Skattebøl reaction under different conditions.

The concise and efficient total syntheses of the naturally-occurring coumarin derivatives gerberinol I, and the pterophyllins 2 and 4, from 5-methyl-4-hydroxycoumarin as a common precursor employing different Casnati-Skattebøl reaction conditions, are reported. The synthesis of the key intermediate coumarin was achieved by the organocatalytic condensation of acetylacetone and crotonaldehyde followed by a LiCl-assisted cyclization, CuCl-promoted aromatization and a final EtCO-mediated cyclization. A Casnati-Skattebøl formylation under high-temperature conditions afforded gerberinol I, whereas milder conditions resulted in an unstable 3-formyl-4-hydroxycoumarin derivative, which was subjected to a basic alumina-mediated one pot O-alkylation with chloroacetone and intramolecular aldolization to furnish pterophyllin 4.

Neocryptolepine: A Promising Indoloisoquinoline Alkaloid with Interesting Biological Activity. Evaluation of the Drug and its Most Relevant Analogs.

Plants are one of the most important resources for the discovery of new drugs. The potential of natural compounds as new drug leads is clearly illustrated by the discovery and development of many modern medicines. This is an encouraging factor that drives natural products research in the vegetable kingdom.

A complete vibrational study on a potential environmental toxicant agent, the 3,3',4,4'-tetrachloroazobenzene combining the FTIR, FTRaman, UV-Visible and NMR spectroscopies with DFT calculations.

In this study 3,3',4,4'-tetrachloroazobenzene (TCAB) was prepared and then characterized by infrared, Raman, multidimensional nuclear magnetic resonance (NMR) and ultraviolet-visible spectroscopies. The density functional theory (DFT) together with the 6-31G(*) and 6-311++G(**) basis sets were used to study the structures and vibrational properties of the two cis and trans isomers of TCAB. The harmonic vibrational wavenumbers for the optimized geometries were calculated at the same theory levels.