Amelia Díaz

• University of the Andes

A new eusdesmane sesquiterpenoid, characterized as 3,5,8a-trimethyl-8-oxo-4,4a,5,6,7,8,8a,9-octahydronaphtho[2,3-b]furan-5-yl acetate (1), has been isolated from the rhizomes of the South African variety of wild ginger (Siphonochilus aethiopicus (Schweinf) B. L. Burtt). The compound was obtained by silica gel column chromatography. Its structure wa...

The one-pot reaction of a chiral aldehyde, p-methoxyaniline or p-fluoroaniline, and triethylborane produces the corresponding alkylated chiral amine with high yields and diastereoisomeric ratios. Stereocontrol is induced by the presence of a heteroatom in the α-position to the aldehyde. In the case of alkylation of imines derived from chiral alipha...

Superparamagnetic iron nanoparticles (SPIONs) have become one of the most useful colloidal systems in nanomedicine. We report here the preparation of new hybrid core@shell systems based on SPION nanoparticles coated with a SiO 2 shell (SPION@SiO 2) and functionalized with carboxyl groups (SPION@SiO 2-COOH). A series of new N-alkylamino-and N-alkyla...

Modification of gold substrates with a stable, uniform and ultrathin layer of biocompatible materials is of tremendous interest for the development of bio‐devices. We present the fabrication of hybrid systems consisting of triangular prism gold nanoparticles (Au@NTPs) covalently covered with tripod‐shaped oligo(p‐phenylenes) featuring trifluorometh...

Here, temperature-sensitive hybrid poly(N-isopropylacrylamide) (pNIPAM) nanosystems with magnetic response are synthesised and investigated for controlled release of 5-fluorouracil (5FU) and oxaliplatin (OXA). Initially, magnetic nanoparticles (@Fe3O4) are synthesised by co-precipitation approach and functionalised with acrylic acid (AA), 3-butenoi...

Polymeric nanofibers (NFs) have been extensively reported as a biocompatible scaffold to be specifically applied in several researching fields, including biomedical applications. The principal researching lines cover the encapsulation of antitumor drugs for controlled drug delivery applications, scaffolds structures for tissue engineering and regen...

We describe design and synthesis of novel tripod-shaped molecules that are potentially capable of monomolecular assembly on noble metal substrates, maintaining, due to their rigidity and specific geometry, the orientation of the functional arm in a perpendicular fashion with respect to the substrate. Using a combination of X-ray photoelectron spect...

A series of new 1-aryl-6,7-dihydroxy tetrahydroisoquinolines with several substitution patterns in the 1-aryl group at C-1 were prepared in good yields. The influence of each substituent on the affinity and selectivity for D1 and D2 dopaminergic receptors was studied. Moreover, N-alkyl salts of these tetrahydroisoquinolines were used as starting ma...

Paclitaxel (PTX), one of the most effective cytotoxins for the treatment of breast and lung cancer, is limited by its severe side effects and low tumor selectivity. In this work, hollow-poly(4-vinylpyridine) (hollow-p4VP) nanoparticles (NPs) have been used for the first time to generate PTX@p4VP NPs, employing a novel technique in which a gold core...

In this review modification of cellulose and alumina membranes are studied. Cellulose membranes are classified by the derivatives used for its modification. General biomedical applications of modified cellulose membranes with organic substrates are studied and their specific applications with organic substrates are also analysed. Review includes pr...

Nanostructured thin films and subsequent biofunctionalization of silicon substrates are essential for the development of biosensors devices. The formation of organic monolayers on silicon substrates via Si-C bound allows specific interactions with biomolecules and presents several advantages like greater detection sensitivity and stability against...

The development of modified surfaces with organic molecules or bioactive molecular structures has become an attractive research field due to the wide application in biomedical and electronic fields. Modification of silicon substrates, based on ultrathin organic films to allow specific interactions with biological targets, is important for the devel...

Tetrahydroisoquinolines are precursors of different types of alkaloids including the [3]benzazepines. These molecules are active of various neurological disorders such as Parkinson´s and Alzheimer´s disease. The discovery of SCH 23390, one of the first selective dopamine D1-like receptor antagonists, and its conformationally restricted analogue SCH...

Nanostructured thin films are essential to develop new biosensor devices, in this sense, to control the orientation and spacing between grafted functional groups on a surface, tripodal oligo (p-phenylene)s have become ideal anisotropic adsorbates due to their shape-persistent and selfstanding characteristics. Here we report the synthesis and charac...

Here we report the synthesis and characterization of several tripod-shaped oligo(p-phenylene)s molecules with legs composed of five and three phenylene units, compounds 1 and 2, respectively. In these structures, each leg is end-capped with an azide group and the terminal functional arm contains an acetylene or bromine group. The presented synthesi...

Here we describe the first seedless synthesis of vinyl-terminated Au nanotriangular prisms (AuNTPs) and nanooctahedra (AuNOC) in aqueous media. This synthesis is performed by chemical reduction of chloroauric acid (HAuCl4) with 3-butenoic acid (3BA) in presence of benzyldimethylammonium chloride (BDAC). The principal novelties of the presented meth...

We present here the synthesis, and the structural and spectroscopic analysis of a non-planar tripod-shaped p-(N,N’-dimethylamino)benzyliden-1,3-indandione (DMABI) chromophore. This novel molecule is composed by a Si core with three incorporated arms, each of them contains a 1,3-indandione derivative with an electron donating (-NMe2) group, thus pro...

Tetrahydroisoquinolines are the most numerous alkaloids in nature. They present phenethylamine structure, which is similar to dopamine, therefore they are able to interact with dopaminergic receptors [1]. We have carried out the synthesis of the tetrahydroisoquinoline 1 as precursor of the tetrahydroisoquinolines 2 y 3, which have been functionaliz...

Abstract: In this paper we report a new strategy of synthesis of isoindolo[2,1-b]isoquinolines. N-(1,2- Diphenylethyl)acetamides prepared from the corresponding deoxybenzoins were used as starting material. Double cascade cyclization of the amides promoted by oxalyl chloride and stannyl chloride afforded the oxidized isoindolo[2,1- b]isoquinolinone...

We report here the synthesis of several tripod-shaped oligo(p-phenylene)s with legs composed of two phenylene units. Each leg is end-capped with a thioacetate group for adhesion to metallic surfaces. An azobenzene chromophore group is present on the functional arm of the tripod. The key step in the synthesis is the Pd-catalyzed Suzuki cross-couplin...

In this article, a new species of salamander of the genus Bolitoglossa (Eladinea) from the cloud forest near La Mucuy in Sierra Nevada de Mérida, Venezuelan Andes, is described. Bolitoglossa mucuyensis sp. nov. differs from all Venezuelan salamanders, except B. orestes, by a larger SVL/TL ratio, and from La Culata salamander B. orestes by a reduced...

Salamanders found at different localities nearby Mérida city, Venezuela, are thus far reported as Bolitoglossa orestes or B. spongai. However, morphological ambiguities among individuals from several populations of both putative species, besides their reported disparate geographical distributions, prompted us to clarify the specific identity of the...

A convenient synthesis for new SCH 23390 analogues bearing different substituents at the C-1 position has been developed by using the diastereoselective Stevens rearrangement. This procedure has provided a good number of new 1,2-disubstituted 1H-3-benzazepines, either through isolation of the isoquinolinium salts or directly by using a new one-pot...

A number of novel analogues of SCH 23390 and SCH 39166 are prepared using the title reaction.

1,2-Disubstituted 2,3,4,5-tetrahydro-1H-3-benzazepines were conveniently obtained by making use of the regio- and diastereoselective Stevens rearrangement of the corresponding isoquinolinium salts with 1,8-diazabicyclo[5 4.0]undec-7-ene in acetonitrile. This procedure has provided a good number of novel analogue compounds of SCH 23390

The one-pot three-component reaction of an aryl aldehyde, an arylamine, and a trialkylborane in the presence of hydrogen peroxide afforded the alkylated arylamines 1 in good yields via oxidized imine–borane complexes. In addition, the versatility of our procedure has been confirmed by the use of enolizable aldehydes, alkylic amines, and cyclic imin...

The total synthesis of the natural compound (8S*,14S*)-8-(4′-hydroxybenzyl)-2,3-dimethoxyberbin-10-ol and its C-8 epimer has been conveniently developed by making use of the diastereoselective Stevens rearrangement of the corresponding N-(arylmethyl)berbinium salts as the key step.

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The reaction of an aldimine with dicyclohexylboron chloride in the presence of hydrogen peroxide gives N-[cyclohexyl(aryl)methyl]arylamines 2 in good yields via oxidized imine–borane complexes. The amines can also be obtained by a three-component reaction involving an arenecarbaldehyde, an arylamine and a dialkylchloroborane reagent. (© Wiley-VCH V...

An improved synthetic approach to protopines based on the sequential Hofmann elimination, hydroboration and oxidation of N-(arylmethyl)berbinium salts has been designed. By using berberine chloride as the starting material, this sequence of reactions has provided two new nonnatural protopines, N-benzyl-N-nordihydroallocriptopine and N-(p-methoxyben...

8-(Arylmethyl)berbines are conveniently obtained through a Stevens rearrangement of the corresponding N-arylmethylberbinium salts with sodium methylsulfinylmethylide in DMSO. This procedure has provided two new nonnatural 8-benzylcanadines stereoselectively, without competition from the Hofmann elimination. (© Wiley-VCH Verlag GmbH & Co. KGaA, 6945...

The transformation of protopines into berbines under improved conditions has been used to synthesize 1-methoxystylopine. Coulteropine, the main alkaloid from Romneya coulteri, was used as the starting protopine to accomplish the stereocontrolled synthesis of both cis and transN-methyl-1-methoxystylopinium salts. The results of ab initio calculation...