Search results for "thesis"
showing 10 items of 4193 documents
Asymmetric Organocatalytic Synthesis of 4-Aminoisochromanones via a Direct One-Pot Intramolecular Mannich Reaction
2016
Synthesis 48(24), 4451 - 4458(2016). doi:10.1055/s-0035-1562522
Appropriateness of surgery performed for abdominal aortic aneurysm at tertiary hospitals in Spain
2021
Background: The aim of this study was to analyze the appropriateness of the type of repair (open or endovascular) performed for abdominal aortic aneurysm (AAA) in five university hospitals in Spain, according to evidence-based recommendations. Methods: A multicenter, retrospective cross-sectional study of patients with AAA who underwent elective open surgical repair (OSR) or endovascular aneurysm repair (EVAR). Data were collected on demographic and clinical variables and type of surgical repair. A pair of vascular surgeons from each participating hospital performed a blinded assessment based on GRADE recommendations. The concordance between the two evaluators and the agreement between thei…
Design, Synthesis and Evaluation of Fluorescent Analogues of Abscisic Acid
2020
A fluorescent analogue of abscisic acid has been prepared by combining (S)‐abscisic acid (ABA) with nitrobenzoxadiazole (NBD) fluorophore using ethanol amine as a linker. Isomerization of the double bond at the side chain of abscisic acid happened during the synthesis. The resulting fluorophore analogues derived from both isomeric compounds entered cells suggesting a wide applicability of the ABA‐NBD conjugates as fluorescent probes to study ABA mechanism of action. The functional properties of the isomeric ABA‐NBD conjugates were tested in vitro, by measuring TNFα expression and nitrite concentration in LPS‐stimulated macrophages and compared with their non‐fluorescent ABA isomers. Rationa…
One-pot cross-enyne metathesis (CEYM)-Diels-Alder reaction of gem-difluoropropargylic alkynes.
2013
Propargylic difluorides 1 were used as starting substrates in a combination of cross-enyne metathesis and Diels–Alder reactions. Thus, the reaction of 1 with ethylene in the presence of 2nd generation Hoveyda–Grubbs catalyst generates a diene moiety which in situ reacts with a wide variety of dienophiles giving rise to a small family of new fluorinated carbo- and heterocyclic derivatives in moderate to good yields. This is a complementary protocol to the one previously described by our research group, which involved the use of 1,7-octadiene as an internal source of ethylene.
Synthesis of Amino-1,2,4-triazoles by Reductive ANRORC Rearrangements of 1,2,4-Oxadiazoles
2010
The reaction of various 1,2,4-oxadiazoles with an excess of hydrazine in DMF has been investigated. 3-Amino- 1,2,4-triazoles are produced through a reductive ANRORC pathway consisting of the addition of hydrazine to the 1,2,4-oxadiazole followed by ring-opening, ring-closure, and final reduction of the 3-hydroxylamino-1,2,4-triazole intermediate. The general applicability of 1,2,4-oxadiazoles ANRORC reactivity is demonstrated also in the absence of C(5)-linked electron-withdrawing groups.
Recent Advances in the Chemistry of 1,2,4-Oxadiazoles
2015
1,2,4-Oxadiazoles experienced an almost 80-year long period of scientific lethargy before they tickled the curiosity of chemists. The study of chemical and photochemical reactivity of 1,2,4-oxadiazoles opened the way to a series of applications in heterocyclic synthesis. Today, 1,2,4-oxadiazoles are known in medicinal chemistry for their use as bioisosters of esters and amides. Furthermore, fluorinated 1,2,4-oxadiazoles have been applied in materials science either by themselves or for the targeted modification of polymers and macromolecules. Overall, the synthesis of 1,2,4-oxadiazoles can be planned to fine-tune their properties for featured applications. Their versatility, either as start…
Reactions of m-Terphenyl-Stabilized Germylene and Stannylene with Water and Methanol: Oxidative Addition versus Arene Elimination and Different React…
2015
Reactions of the divalent germylene Ge(ArMe6)2 (ArMe6 = C6H3-2,6-{C6H2-2,4,6-(CH3)3}2) with water or methanol gave the Ge(IV) insertion product (ArMe6)2Ge(H)OH (1) or (ArMe6)2Ge(H)OMe (2), respectively. In contrast, its stannylene congener Sn(ArMe6)2 reacted with water or methanol to produce the Sn(II) species {ArMe6Sn(μ-OH)}2 (3) or {ArMe6Sn(μ-OMe)}2 (4), respectively, with elimination of ArMe6H. Compounds 1–4 were characterized by IR and NMR spectroscopy as well as by X-ray crystallography. Density functional theory calculations yielded mechanistic insight into the formation of (ArMe6)2Ge(H)OH and {ArMe6Sn(μ-OH)}2. The insertion of an m-terphenyl-stabilized germylene into the O–H bond was…
Painful prosthesis: approaching the patient with persistent pain following total hip and knee arthroplasty.
2013
BACKGROUND: Symptomatic severe osteoarthritis and hip osteoporotic fractures are the main conditions requiring total hip arthroplasty (THA), whereas total knee arthroplasty (TKA) is mainly performed for pain, disability or deformity due to osteoarthritis. After surgery, some patients suffer from "painful prosthesis", which currently represents a clinical problem. METHODS: A systematic review of scientific literature has been performed. A panel of experts has examined the issue of persistent pain following total hip or knee arthroplasty, in order to characterize etiopathological mechanisms and define how to cope with this condition. RESULTS: Four major categories (non infective, septic, othe…
Synthesis, NMR spectral and structural studies on mixed ligand complexes of Pd(II) dithiocarbamates: First structural report on palladium(II) dithioc…
2016
Abstract Three new mixed ligand complexes of palladium(II) dithiocarbamates; [Pd(4-dpmpzdtc)(PPh3)(SCN)] (1), [Pd(4-dpmpzdtc)(PPh3)Cl] (2) and [Pd(bzbudtc)(PPh3)Cl] (3), (where, 4-dpmpzdtc = 4-(diphenylmethyl)piperazinecarbodithioato anion, bzbudtc = N-benzyl-N-butyldithiocarbamato anion and PPh3 = triphenylphosphine) have been synthesized from their respective parent dithiocarbamates by ligand exchange reactions and characterized by IR and NMR (1H, 13C and 31P) spectroscopy. IR and NMR spectral data support the isobidentate coordination of the dithiocarbamate ligands in all complexes (1–3) in solid and in solution, respectively. Single crystal diffraction analysis of complexes 1–3 evidence…
Reproducibility in Electroorganic Synthesis—Myths and Misunderstandings
2021
Abstract The use of electric current as a traceless activator and reagent is experiencing a renaissance. This sustainable synthetic method is evolving into a hot topic in contemporary organic chemistry. Since researchers with various scientific backgrounds are entering this interdisciplinary field, different parameters and methods are reported to describe the experiments. The variation in the reported parameters can lead to problems with the reproducibility of the reported electroorganic syntheses. As an example, parameters such as current density or electrode distance are in some cases more significant than often anticipated. This Minireview provides guidelines on reporting electrosyntheti…