Andrea B. J. Bracca

Molecular Detection of Histoplasma capsulatum var. capsulatum in Human Clinical Samples

ABSTRACT We developed a seminested PCR for the diagnosis of histoplasmosis that amplifies a portion of the Histoplasma capsulatum H antigen gene. This assay is highly sensitive and specific, being able to detect genomic material corresponding to less than 10 yeast cells without cross-reaction against other bacterial or fungal pathogens.

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. Minimum inhibitory concentrations and minimum fungicidal concentrations were determined, and the morphology of the colonies was examined microscopically. In liquid medium, it was found that pterophyllin 4 exhibited selective fungicidal activity toward M. fructicola, whereas its congener pterophyllin 2 proved to be less potent and not selective and the 5-desmethyl analog of pterophyllin 4 displayed a different activity profile. Morphological changes were observed in the colonies exposed to pterophyllin 4. The results highlighted the importance of small structural features for the antifungal behavior and also suggested that, in Nature, the pterophyllins may act as plant defenses against pathogens.

First total synthesis of the only known 2-isopropyliden-2H-benzofuran-3-one isolated from V. luetzelburgii

The first total synthesis of 5-(1-hydroxy-1-ethyl)-2-isopropyliden-2H-benzofuran-3-one, is reported in its racemic and in one of its optically active [(S)-(−)] forms. This heterocycle, isolated from Verbesina luetzelburgii, is the only known 2-isopropyliden-2H-benzofuran-3-one produced by species of Verbesina. The sequence took place in eight steps and 19% overall yield (up to 33% for the chiral form), from 4′-hydroxyacetophenone. It entailed carbonyl group protection as the 1,3-dioxolane and a phenol ortho formylation, followed by a Williamson etherification with chloroacetone and an organocatalytic cross-aldolization, to afford a 2-acetyl-2,3-dihydrobenzofuran-3-ol intermediate. The latter underwent a methyl Grignard addition to the carbonyl moiety, followed by selective oxidation of the benzylic alcohol and deprotection, resulting in a β-hydroxy diketone derivative. A MsCl-assisted dehydration of the tertiary alcohol, established the isopropylidene motif, whereas the syntheses culminated by chemical or enzymatic (carrot, celeriac) selective reductions of the exocyclic carbonyl group.

A convenient and eco-friendly cerium(III) chloride-catalysed synthesis of methoxime derivatives of aromatic aldehydes and ketones

The use of CeCl3·7H2O as an efficient and eco-friendly promoter for the convenient synthesis of methoximes derived from aromatic aldehydes and ketones, is reported. The transformations entail the use of equimolar amounts of MeONH2·HCl and NaOAc in EtOH at 50°C, and no special precautions are needed with regard to the presence of oxygen. The scope and limitations of the transformation were studied and a reaction mechanism was proposed.

Experimental and theoretical studies of the [3,3]-sigmatropic rearrangement of prenyl azides

[3,3]-Sigmatropic rearrangement of isoprenyl azides has been extensively investigated in an experimental and theoretical level. Prenylazides with different chain lengths and phenyl prenylazide have been synthesized. NMR analysis of each azide has been made to determine the equilibrium composition, showing the predominance of primary allyl azides over the tertiary ones and E over Z isomer, regardless of the chain length, temperature, solvent or the regiochemistry of the precursor isoprenyl alcohol. It was determined that phenyl prenylazides do not experience [3,3]-sigmatropic rearrangement. In order to rationalize the experimental results and to gain insight in the mechanism of the [3,3]-sigmatropic rearrangement of prenylazides a theoretical study was performed using density functional theory and the QTAIM approach.

Efficient total synthesis of neocryptolepine and synthetic access to 6-methylquinindoline from a common intermediate

A convenient approach toward the indoloquinolines neocryptolepine and 6-methylquinindoline from na common intermediate, is reported. Both sequences, designed for maximum use of accessible reagents nand robust conditions, are straightforward and efficient. They involved the amidation of 2- naminobenzaldehyde (prepared by iron-mediated reduction of 2-nitrobenzaldehyde) with 2- nnitrophenylacetic acid, followed by a K2CO3-assisted cyclization to form a 3-(2-nitrophenyl)quinolin-2- none as the common precursor. Me2CO3-mediated N-methylation of the lactam, reduction of the nitro nmoiety and final cyclization resulted in 55% overall yield of neocryptolepine, whereas cyclocondensation nand N-methylation afforded 79% overall yield of 6-methyl quinindoline. Thus, the sequences toward the ntargets entailed two POCl3-promoted C–N bond forming reactions, two Fe-mediated nitro group nreductions and two base-promoted transformations.

Economical and Convenient Carbonyl Transposition Approach Toward a 2‐Arylcycloheptanone Derivative

Abstract A convenient, straightforward, and easy access to 2(2,3‐dimethoxy‐phenyl)cycloheptanone, which employs an heteroatom‐facilitated ortho‐lithiation coupled to a carbonyl transposition strategy, is reported. The synthetic approach avoids using very expensive reagents or difficult‐to‐prepare starting materials.