Yangen Huang

Synthesis of γ-Monofluorinated Goniothalamin Analogues via Regio- and Stereoselective Ring-Opening Hydrofluorination of Epoxide

A stereoselective synthesis of the biologically interesting γ-monofluorinated goniothalamin analogue 2a was described. The features of the synthesis included regioselective reduction of the unprotected hydroxypropynyl moiety of compound 10 by Red-Al, asymmetric Sharpless epoxidation of allyl alcohol 11, and regio- and stereoselective ring-opening hydrofluorination of the hydroxypropynyl epoxide 14 with Et(3)N·3HF in high ee and dr. The chiral hydroxypropynyl fluorohydrin 15 was used as a valuable building block for preparation of a range of γ-monofluorinated α,β-unsaturated δ-lactones.

Synthesis of Trifluoromethylthiolated Alkenes and Ketones by Decarboxylative Functionalization of Cinnamic Acids

A tunable decarboxylative trifluoromethylthiolation of cinnamic acids with AgSCF3 was developed to afford trifluoromethylthiolated alkenes or ketones by using transition metal-mediated conditions.

Copper-Catalyzed, Stereoselective Bis-trifluoromethylthiolation of Propiolic Acid Derivatives with AgSCF3

A copper-catalyzed chemo- and stereoselective oxidative bis-trifluoromethylthiolation of propiolic acid derivatives was achieved by using carboxylic acid as the activating group and formic acid as a cosolvent. The reaction of propiolic acid derivatives and AgSCF3 in the presence of (NH4)2S2O8 and catalytic Cu(OAc)2 in MeCN/HCO2H afforded bis-trifluoromethylthiolated acrylic acids in moderate to excellent yields with E selectivity. Further derivatization of the resultant products gave a series of polysubstituted SCF3-containing alkenes.

Anti-crease finishing of cotton fabrics based on crosslinking of cellulose with acryloyl malic acid

Maleic acid (MA) has been explored to replace formaldehyde-based dimethylol dihydroxy ethylene urea (DMDHEU) for cotton anti-crease finishing. However, the resilience of treated fabrics was not satisfactorily improved. In this study, acryloyl malic acid (AMA) was synthesized and applied on fabrics as a novel crosslinking agent. The results showed that both crease recovery angle and whiteness index of treated samples were higher than those of MA in the presence/absence of catalyst sodium hypophosphite (SHP). Chemical structure of AMA was confirmed by NMR and MS spectra. The possible crosslinking mechanism between AMA and cellulose was investigated by means of (13)C NMR, MS, FTIR and phosphorus content analyses. It was found that AMA could form ester bonds with cellulose by formation of anhydride intermediate. Meanwhile, additional reaction of double bonds on AMA with another molecule or PH of SHP residual has also contributed to the crosslinking. A reaction equation was proposed based on the analyses.

Copper-Assisted Oxidative Trifluoromethylthiolation of 2,3-Allenoic Acids with AgSCF3

The oxidative trifluoromethylthiolation of 2,3-allenoic acids with AgSCF3 in the presence of (NH4)2S2O8 and catalytic copper salt was investigated. A series of 4-aryl-2,3-allenoic acids underwent radical trifluoromethylthiolation/intramolecular cyclization to afford β-trifluoromethylthiolated butenolides, which were conveniently transformed into trifluoromethylthiolated furan derivatives. In contrast, 2-monosubstituted 2,3-allenoic acids were converted into the corresponding 3,4-bis(trifluoromethylthio)but-2-enoic-acids under similar reaction conditions.

Synthesis and antibiofouling properties of crosslinkable copolymers grafted with fluorinated aromatic side chains

To obtain highly effective antifouling coatings, a series of functional ternary copolymers grafted with short fluoroalkyl or perfluoropolyether modified fluorinated aromatic side chains and cross-linkable functional groups were prepared via radical polymerization. Nuclear magnetic resonance (NMR), Fourier transform infrared (FT-IR), gel permeation chromatography (GPC), X-ray photoelectron spectroscopy (XPS) and thermogravimetric analysis (TGA) were used to characterize the fluoropolymers. The surface properties of the fluoropolymer coatings on cotton fabric, aluminum plates and glass slides were studied. The results indicate that the fluoropolymers show good thermal stabilities (Td > 303 °C), and the hydrophobicity of the fluoropolymer coatings was increased with the increase of fluorinated monomer content (water contact angle on cotton fabric was up to 144°). The antifouling characteristics were investigated by Escherichia coli and Staphylococcus aureus attachment studies. The fluoropolymers exhibited excellent antibacterial activity against E. coli and S. Aureus. The fluoropolymers might be used as promising environmentally benign marine antifouling coating materials due to their high thermal stability, hydrophobicity and antifouling effect.

Synthesis of aryl triflones by insertion of arynes into C–SO2CF3 bonds

A new approach toward the synthesis of aryl triflones was achieved by the formal insertion of arynes into C–SO2CF3 bonds. This reaction proceeds through addition of CF3SO2-containing nucleophiles to the in situ generated arynes and subsequent intramolecular rearrangement.

Synthesis and characterization of photoresponsive POSS-based polymers and their switchable water and oil wettability on cotton fabric

Fast photoresponsive polymers containing polyhedral oligomeric silsesquioxane (POSS) and fluorinated azobenzene groups were successfully prepared via radical polymerization and characterized by NMR, FTIR, XRD, GPC, TGA, etc. The photoresponsive properties of the polymers were investigated through ultraviolet-visible absorption spectra. The trans–cis photoisomerization of the polymers in solution conformed to a first-order reaction kinetics equation. Superhydrophobicity and high oleophobicity of the cotton fabric coated with the polymer was observed when the POSS mole ratio was 3.0%. More importantly, the surface wettability of both water and oil on the coated fabrics could be intelligently controlled by applying UV irradiation in a short time.

One-pot syntheses of N-(α-fluorovinyl)azole derivatives from N-(diphenylmethylene)-2,2,2-trifluoroethanamine

N-(Diphenylmethylene)-2,2,2-trifluoroethanamine acts as a versatile fluorine-containing building block, and from which N-(α-fluorovinyl)azole derivatives were readily prepared in good yields with relatively high stereoselectivity by using various N–H containing heterocycles as nucleophiles via vinylic substitution reactions (SNV) in the presence of LDA and K3PO4 in a one-pot process.

Transition-Metal-Free Decarboxylation of 3,3,3-Trifluoro-2,2-dimethylpropanoic Acid for the Preparation of C(CF3)Me2-Containing Heteroarenes

The direct synthesis of C(CF3)Me2-substituted heteroarenes by decarboxylative 1,1-dimethyltrifluoroethylation of heteroarenes with 3,3,3-trifluoro-2,2-dimethylpropanoic acid is reported. This method does not need the transition-metal catalyst, and the base is crucial for this reaction. A series of previously unknown C(CF3)Me2-containing heteroarenes were obtained in high yields and have potential applications in the drug discovery process.