Search results for "SELECTIVITY"
showing 10 items of 1148 documents
Angular Regioselectivity in the Reactions of 2-Thioxopyrimidin-4-ones and Hydrazonoyl Chlorides : Synthesis of Novel Stereoisomeric Octahydro[1,2,4]t…
2020
The regioselective synthesis of cis and trans stereoisomers of variously functionalized octahydro[1,2,4]triazolo[4,3-a]quinazolin-5-ones was performed. The 2-thioxopyrimidin-4-ones used in the synthesis reacted with hydrazonoyl chlorides in a regioselective manner to produce the angular regioisomers [1,2,4]triazolo[4,3-a]quinazolin-5-ones rather than the linear isomers [1,2,4]triazolo[4,3-a]quinazolin-5-ones. The synthesis process took place with electronic control. The angular regiochemistry of the products was confirmed by X-ray experiments and two-dimensional NMR studies.
A Novel Halogen Bond Acceptor : 1-(4-Pyridyl)-4-Thiopyridine (PTP) Zwitterion
2020
Sulfur is a widely used halogen bond (XB) acceptor, but only a limited number of neutral XB acceptors with bifurcated sp3-S sites have been reported. In this work a new bidentate XB acceptor, 1-(4-pyridyl)-4-thiopyridine (PTP), which combines sp3-S and sp2-N acceptor sites, is introduced. Three halogen bonded cocrystals were obtained by using 1,4-diiodobenzene (DIB), 1,4-diiodotetrafluorobenzene (DIFB), and iodopentafluorobenzene (IPFB) as XB donors and PTP as acceptor. The structures of the cocrystals showed some XB selectivity between the S and N donors in PTP. However, the limited contribution of XB to the overall molecular packing in these three cocrystals and the results from DSC measu…
Selective Synthesis of Z -Silyl Enol Ethers via Ni-Catalyzed Remote Functionalization of Ketones
2021
Journal of the American Chemical Society : JACS 143(22), 8375-8380 (2021). doi:10.1021/jacs.1c01797
From Overstoichiometric to Substoichiometric Enantioselective Protonation with 2-Sulfinyl Alcohols: A View in Perspective
2005
A general study of the enantioselective protonation of prochiral enolates with 2-sulfinyl alcohols is reported. The modification of reaction conditions to reduce drastically the amount of chiral proton source needed to obtain a good enantiomeric excess is reported. The effects of the different factors controlling the stereoselectivity are clearly established. Different protocols for enolate generation are compared.
Triazolopyridines 22.1 Description of new 7,9-di(2-pyridyl)[1,2,3]triazolo[5',1':6,1]pyrido[3,2-d]pyrimidines
2002
The new heteroaromatic compounds, 7,9-di(2-pyridyl)(1,2,3)triazolo(5',1':6,1)pyrido(3,2-d) pyrimidines 11a-c, were synthesized in two steps from readily available triazolopyridines 1a-c. Regioselective lithiation of 1a-c followed by treatment with 2-cyanopyridine gave a mixture of compounds 5a-c, and 11a-c in moderate to low yields, together with gums. Similar reactions with the triazolopyridine 1d gave as the only identified compound the triazolopyridine derivative 5d.
“One Ring to Bind Them All”—Part II: Identification of Promising G-Quadruplex Ligands by Screening of Cyclophane-Type Macrocycles
2010
A collection of 26 polyammonium cyclophane-type macrocycles with a large structural diversity has been screened for G-quadruplex recognition. A two-step selection procedure based on the FRET-melting assay was carried out enabling identification of macrocycles of high affinity (ΔT1/2up to30°C) and high selectivity for the human telomeric G-quadruplex. The four selected hits possess sophisticated architectures, more particularly the presence of a pendant side-arm as well as the existence of a particular topological arrangement appear to be strong determinants of quadruplex binding. These compounds are thus likely to create multiple contacts with the target that may be at the origin of their h…
Direct radiofluorination of [18F]MH.MZ for 5-HT2A receptor molecular imaging with PET
2012
Imaging the serotonin 2A neuroreceptor with positron emission tomography has been carried out with [11C]MDL 100907 and [18F]altanserin for years. Recently, the MDL 100907 analogue [18F]MH.MZ was developed by combining the increased selectivity profile of MDL 100907 and the favourable radiophysical properties of fluorine-18. Here, we want to report the synthesis of [18F]MH.MZ via direct radiofluorination. Unfortunately, the direct radiofluorination did not have any significant benefits over the indirect labelling method. This is mainly because the precursor for the direct labelling approach is not completely stable and slowly decomposes. However, only one HPLC separation is necessary for the…
Stereoselective Synthesis of the Antiprotozoal Lactone Passifloricin A and Seven Isomers Thereof
2004
The conjugated delta-lactone passifloricin A, a natural product with antiprotozoal activity, and seven isomers thereof have been synthesized in enantiopure form. It has been shown in this way that the proposed structure for the natural compound was erroneous. The correct structure is now evidenced. Key steps of the syntheses were asymmetric Brown-type aldehyde allylations and ring-closing metatheses.
Anthropometric measurements and nutritional assessment in autism spectrum disorders: A systematic review
2015
Abstract Adequate nutrient intake is essential for health. Due to food selectivity and restrictive diets, people with autism spectrum disorder (ASD) may have impaired nutritional status, which could affect their growth. We present a systematic review of publications (1970–2013) on anthropometric measurements and nutritional assessment in this population. The limited research published on growth and nutritional status has found contradictory results. Nutritional assessment has indicated limited food variety in the ASD population but has not confirmed significant differences with respect to recommended intakes or controls. In addition to the lack of control groups, studies in this area have s…
From 1D coordination polymers to Metal Organic Frameworks by the use of 2-pyridyl oximes.
2020
The synthesis and characterization of coordination polymers and metal&ndash