Search results for "Synthon"
showing 10 items of 50 documents
Comparison of the polymorphs and solvates of two analogous fungicides—a case study of the applicability of a supramolecular synthon approach in cryst…
2011
The polymorphism and solvate formation of thiophanate-ethyl (TE), a fungicidal active, were investigated by solvent crystallization and compared to a close analogue, thiophanate-methyl (TM). Four polymorphs and seven solvates of TE were found and structurally compared with the previously found two polymorphs and fourteen solvates of TM by analyzing the hydrogen bonding patterns and using fingerprint plots, packing coefficients and lattice energies. TE and TM have the same functional groups that can build identical supramolecular synthons. Despite the strong similarities, the polymorphs and solvates of the two actives show significant differences in hydrogen bonding and packing. The results …
18F-labeling and evaluation of novel MDL 100907 derivatives as potential 5-HT2A antagonists for molecular imaging.
2009
Abstract Introduction The serotonergic system, especially the 5-HT2A receptor, is involved in various diseases and conditions. It is a very interesting target for medicinal applications. Methods Two novel 5-HT2A tracers, namely, [ 18 F]DD-1 and the enantiomeric pure ( R )-[ 18 F]MH.MZ, were radiolabeled by 18 F-fluoroalkylation of the corresponding desmethyl analogue. In vitro binding autoradiography on rat brain slices was performed to test the affinity and selectivity of these tracers. Moreover, first μPET experiments of ( R )-[ 18 F]MH.MZ were carried out in Sprague-Dawley rats. Results [ 18 F]DD-1 ( K i =3.23 nM) and ( R )-[ 18 F]MH.MZ ( K i =0.72 nM) were 18 F-fluoroalkylated by the se…
Halogen bonding stabilizes a cis-azobenzene derivative in the solid state : A crystallographic study
2017
Crystals oftrans- andcis-isomers of a fluorinated azobenzene derivative have been prepared and characterized by single-crystal X-ray diffraction. The presence of F atoms on the aromatic core of the azobenzene increases the lifetime of the metastablecis-isomer, allowing single crystals of thecis-azobenzene to be grown. Structural analysis on thecis-azobenzene, complemented with density functional theory calculations, highlights the active role of the halogen-bond contact (N...I synthon) in promoting the stabilization of thecis-isomer. The presence of a long aliphatic chain on the azobenzene unit induces a phase segregation that stabilizes the molecular arrangement for both thetrans- andcis-i…
A Decade of Advance in the Asymmetric Vinylogous Mannich Reaction
2016
When the principle of vinylogy is applied to imines as electrophiles, the so-called vinylogous Mannich reaction (VMR), γ-aminocarbonyl (such as butenolides) and β-aminocarbonyl compounds are generated in a very efficient manner. The asymmetric version of this vinylogous Mannich reaction gives access to highly functionalized chiral synthons, which are suitable for further transformations. The versatility of this methodology is exemplified with the synthesis of several alkaloids and natural products. 1 Introduction 2 Asymmetric Vinylogous Mannich Reactions (VMR) with 2-Silyloxyfurans and 2-Silyloxypyrroles 3 Asymmetric VMR with Acyclic Silyl Dienolates and Silyl Dienol Ketene Acetals 4 Asymm…
A Generalized Synthesis of 3-Amino-5-aryl-, 3-Amino-5-polyfluorophenyl-, and 3-Amino-5-alkyl-1,2,4-oxadiazoles through Ring-degenerate Rearrangements
2002
A generalized synthesis of 3-amino-5-aryl-, 3-amino-5-poly- fluorophenyl- and 3-amino-5-alkyl-1,2,4-oxadiazoles has been developed starting from the 3-amino-5-methyl-1,2,4-oxadiazole as a common synthon. Aroylation or alkanoylation of this aminooxadiazole, followed by thermally- induced ring-degenerate equilibration of resulting 3-acylamino compounds, and final acid hydrolysis of the 3-acetylamino-5-aryl- (or 5-polyfluorophenyl-), or 3- acetylamino-5-alkyl-1,2,4-oxadiazoles counterpart which is formed, gave the expected 3-amino-5-substituted 1,2,4-oxadiazoles. In the case of some 3- aroylamino compounds, yields of final 3-amino-5-aryloxadiazoles are higher than that expected on the basis of…
Crystal and Molecular Structure and Stability of Isoniazid Cocrystals with Selected Carboxylic Acids
2013
Reaction of isoniazid with benzoic acid, sebacic acid, suberic acid, and cinnamic acid results in formation of cocrystals. Two polymorphs of isoniazid–suberic acid and two polymorphs of isoniazid–cinnamic acid cocrystals were isolated. Crystal structure analysis shows the presence of a pyridine–carboxylic acid synthon in the studied cocrystals. The hydrazide group of isoniazid participates in N–H···O and N–H···N hydrogen bond formation, producing different supramolecular synthons. The stability study of isoniazid cocrystals has been performed over a 22 week period. A comparison of melting points of isoniazid–dicarboxylic acid 2:1 cocrystals shows the decrease of melting point with an increa…
Enantioselective synthesis of herbertane sesquiterpenes: synthesis of (−)-α-formylherbertenol
2000
Abstract The synthesis of 4-hydroxy-3-[(1 S )-1,2,2-trimethylcyclopentyl]benzaldehyde [(−)-α-formylherbertenol 1 ], a herbertane-type sesquiterpene isolated from the leafy liverwort Herberta adunca , from β-cyclogeraniol is described. The synthesis is based on the previously described preparation of an enantiopure 1,2,2-trimethylcyclopentane synthon from which the characteristic aromatic moiety of 1 is elaborated, using a Robinson annulation and a palladium-catalysed methoxycarbonylation of an aryl triflate as key synthetic steps. The synthesis of the natural sesquiterpene (−)-α-herbertenol, also a natural sequiterpene, using the same methodology is also described.
Synthesis of novel WAY 100635 derivatives containing a norbornene group and radiofluorination of [18F]AH1.MZ as a serotonin 5-HT1Areceptor antagonist…
2009
5-HT1A receptors are involved in a variety of psychiatric disorders and in vivo molecular imaging of the 5-HT1A status represents an important approach to analyze and treat these disorders. We report herein the synthesis of three new fluoroethylated 5-HT1A ligands (AH1.MZ, AH2.MZ and AH3.MZ) as arylpiperazine derivatives containing a norbornene group. AH1.MZ (Ki= 4.2 nM) and AH2.MZ (Ki=30 nM) showed reasonable in vitro affinities to the 5-HT1A receptor, whereas AH3.MZ appeared to be non-affine toward the 5-HT1A receptor. The receptor profile of AH1.MZ and AH2.MZ showed selectivity within the 5-HT system. 18F-labelling via [18F]FETos to [18F]AH1.MZ was carried out in radiochemical yields of …
Efficient synthesis of new C-functionalized macrocyclic polyamines
2010
A powerful synthetic route for the preparation of new poly-azamacrocycles, valuable precursors of bifunctional chelating agents with applications in nuclear medicine, is reported. The desired functional group was introduced onto the macro-cycle backbone during the cyclization step, thus avoiding the tedious preparation of a C-functionalized synthon. The regioselective reaction of macrocycles bearing an aminomethyl pendant arm with aldehydes is also described.
ChemInform Abstract: Benzothietes. Versatile Synthons for the Preparation of Heterocycles
2010
Abstract Thermal or photochemical ring opening transforms benzo[b]thiete to o-thiobenzoquinonemethide, a highly reactive 8π electron system. Cycloaddition reactions or linear additions with subsequent cyclizations lead to larger heterocyclic rings. A variety of compounds containing sulfur and possibly further heteroatoms like nitrogen, oxygen or phosphorus in normal, medium and large ring systems can be synthesized on this route.