Project description:In the title compound, C(20)H(22)N(2)O(2), the cyclo-hexane ring adopts a chair conformation and the two N atoms bonded to salicyl-idene groups are in cis positions. Both hy-droxy groups are involved in intra-molecular O-H⋯N hydrogen bonding and the two benzene rings form a dihedral angle of 60.5 (1)°.
Project description:The multicomponent coupling reaction of catechol, ammonium acetate, and benzyl alcohol/benzyl methyl ether in the presence of a Fe(III) catalyst precursor afforded benzoxazole derivatives in good to excellent yields. The notable features of this protocol are abundant availability of the catalyst system, large-scale synthesis, high diversity, and high yields of products.
Project description:The stereoselective construction of 1,2-cis furanosidic linkage is synthetically challenging. A strategy that applies to all furanose types remains elusive. In this work, a solution is developed based on gold catalysis and the deployment of the directing-group-on-leaving-group strategy, where a basic oxazole group in the gold-activated leaving group facilitates the stereoinvertive attack by glycosyl acceptors. In addition to exhibiting good to excellent 1,2-cis selectivities, these furanosylation reactions are high-yielding and mostly complete in 30 min to 2 h. A broad range of 1,2-cis-furanosides is prepared. Although some are uncommon, the ease of access enabled by this approach presents new opportunities to study their applications in medicine and materials research.
Project description:The title compound, C(7)H(14)O(2), is a vicinal diol derived from cyclo-heptane with cis-orientated hydr-oxy groups. The mol-ecules shows no non-crystallographic symmetry. The O-C-C-O torsion angles of both mol-ecules present in the asymmetric unit [-66.4 (2) and -66.9 (2)°] are similar to those in trans-configured cyclo-hexane derivatives (including pyran-oses) as well as rac-trans-cyclo-heptane-1,2-diol, but smaller than those in trans-configured cyclo-pentane derivatives (including furan-oses). In the crystal structure, O-H⋯O hydrogen bonds furnish the formation of sheets parallel to [110].
Project description:The stereoselective introduction of glycosidic bonds is of paramount importance to oligosaccharide synthesis. Among the various chemical strategies to steer stereoselectivity, participation by either neighboring or distal acyl groups is used particularly often. Recently, the use of the 2,2-dimethyl-2-(ortho-nitrophenyl)acetyl (DMNPA) protection group was shown to offer enhanced stereoselective steering compared to other acyl groups. Here, we investigate the origin of the stereoselectivity induced by the DMNPA group through systematic glycosylation reactions and infrared ion spectroscopy (IRIS) combined with techniques such as isotopic labeling of the anomeric center and isomer population analysis. Our study indicates that the origin of the DMNPA stereoselectivity does not lie in the direct participation of the nitro moiety but in the formation of a dioxolenium ion that is strongly stabilized by the nitro group.
Project description:Aromatic cation activation is a useful strategy to promote deoxyfunctionalization; however, the deoxyfluorination of alcohols with cyclopropenium cation remains an unsolved problem due to the weak nucleophilicity of fluoride ion. Here we report the use of 3,3-difluoro-1,2-diarylcyclopropenes (CpFluors) as easily accessible and reactivity-tunable deoxyfluorination reagents. The electronic nature of CpFluors is critical for fluorination of monoalcohols via alkoxycyclopropenium cations, and CpFluors with electron-rich aryl substituents facilitate the transformation with high efficiency; however, selective monofluorination of 1,2- and 1,3-diols, which proceeds via cyclopropenone acetals, is less dependent on the electronic nature of CpFluors. Moreover, CpFluors are more sensitive to the electronic nature of alcohols than many other deoxyfluorination reagents, thus fluorination of longer diols can be achieved selectively at the relatively electron-rich position. This research not only unveils the first example of deoxyfluorination reagents that contain an all-carbon scaffold, but also sheds light on the divergent reactivity of cyclopropenium cation in deoxyfunctionalization of alcohols.
Project description:In the title compound, C(13)H(13)N(3), the cyano groups at the 2- and 5-positions are eclipsed with each other. The phenyl ring is disordered over two sets of sites, with refined occupancies of 0.520?(5) and 0.480?(5). The angles between the mean plane of the pyrrolidine ring and the two cyano groups are 71.7?(9) and 75.0?(12)°.
Project description:A new method for the synthesis of α-trifluoromethylated tertiary alcohols bearing coumarins is described. The reaction of 3-(trifluoroacetyl)coumarin and pyrrole provided the target compounds with high yields under catalyst-free, mild conditions. The crystal structure of compound 3fa was investigated by X-ray diffraction analysis. The biological activities, such as in vitro antifungal activity of the α-trifluoromethylated tertiary alcohols against Fusarium graminearum, Fusarium oxysporum, Fusarium moniliforme, Rhizoctonia solani Kuhn, and Phytophthora parasitica var nicotianae, were investigated. The bioassay results indicated that compounds 3ad, 3gd, and 3hd showed broad-spectrum antifungal activity in vitro. Compound 3cd exhibited excellent fungicidal activity against Rhizoctonia solani Kuhn, with an EC50 value of 10.9 μg/mL, which was comparable to that of commercial fungicidal triadimefon (EC50 = 6.1 μg/mL). Furthermore, molecular docking study suggested that 3cd had high binding affinities with 1W9U, like argifin.
Project description:The title Schiff base compound, C(14)H(10)Cl(2)N(2), crystallizes with one half-mol-ecule in the asymmetric unit. The mid-point of the N-N bond [1.418 (3) Å] lies on an inversion centre. The mol-ecular skeleton is approximately planar, the largest deviation from the mean plane being 0.143 (4) Å for the N-bonded C atom. The crystal packing exhibits no classical inter-molecular hydrogen bonds.