Synthesis of 3‐phenyl‐5‐(trifluoromethyl)isoxazole and 5‐phenyl‐3‐(trifluoromethyl)isoxazole

Reaction of 4,4,4‐trifluoro‐1‐phenyl‐1,3‐butanedione with hydroxylamine led to the formation of 5‐hydroxy‐3‐phenyl‐5‐(trifluoromethyl)‐4,5‐dihydroisoxazole which was dehydrated to 3‐phenyl‐5‐(trifluoro‐methyl)isoxazole. This isomer can also be synthesized by reaction of 4‐chloro‐4‐phenyl‐1,1,1‐trifluoro‐3‐buten‐2‐one with sodium azide. The regioisomer, 5‐phenyl‐3‐(trifluoromethyl)isoxazole was synthesized by reaction of 1,1,1‐trifluoro‐4‐phenylbut‐3‐yn‐2‐one with hydroxylamine and by the reaction of 3‐chloro‐1‐phenyl‐4,4,4‐trifluorobut‐2‐en‐1‐one with sodium azide. Both isomers were characterized by mass and NMR spectroscopy.     

A Facile One‐Pot Three‐Component Synthesis of 5‐(Trifluoromethyl)‐4,7‐dihydro‐[1,2,4]‐triazolo[1,5‐a]pyrimidine Derivatives in Ionic Liquid

An efficient one‐pot synthesis of 5‐(trifluoromethyl)‐4,7‐dihydro‐7‐aryl‐[1,2,4]triazolo[1,5‐a]pyrimidine derivatives was performed via the reaction of aryl aldehyde, 3‐amino‐1,2,4‐triazole and ethyl 4,4,4‐trifluoro‐3‐oxobutanoate or 4,4,4‐trifluoro‐1‐phenylbutane‐1,3‐dione in ionic liquid. This method has the advantages of short synthetic route, operational simplicities, mild reaction conditions, high yields and eco‐friendliness.     

Synthesis of trifluoromethylated pyrido[2,3‐d]pyrimidine‐2,4‐diones from 6‐aminouracils and trifluoromethylated pyrazolo[3,4‐b]‐pyridines from 5‐aminopyrazoles

5 or 7‐Trifluoromethyl‐1,2,3,4‐tetrahydropyrido[2,3‐d]pyrimidine‐2,4‐diones 3 , 5 , 10 , 13 and 4‐ or 6‐trifluoromethylpyrazolo[3,4‐b]pyridines 15 , 16 , 19 , 21 were prepared from 6‐aminouracils and 5‐aminopyrazoles, respectively, in good yields by the use of building blocks such as 4,4,4‐trifluoro‐1‐phenyl‐1,3‐butanedione, 1,1,1‐trifluoro‐4‐phenyl‐3‐buten‐2‐one, 4‐ethoxy‐1,1,1‐trifluoro‐3‐buten‐2‐one, and ethyl trifluoroacetoacetate.     

Solvent‐Free Synthesis of 2‐(Phenylamino)‐4‐(trifluoromethyl)‐1,6‐dihydropyrimidine Derivatives Catalyzed by Sulfamic Acid

A series of 2‐(phenylamino)‐4‐(trifluoromethyl)‐1,6‐dihydropyrimidine derivatives were synthesized efficienly via the reaction of aryl aldehyde, ethyl 4,4,4‐trifluoro‐3‐oxobutanoate and 1‐phenylguanidine carbonate catalyzed by sulfamic acid under solvent‐free conditions. This protocol has the advantages of mild condition, high yields and environmentally benign procedure.     

Copper‐catalyzed cross‐coupling of α‐seleno‐acylzirconocene chloride with haloalkynes: Synthesis of α‐seleno‐substituted vinyl alkynyl ketones

The copper‐catalyzed cross‐coupling reaction of α‐selenoacylzirconocene chloride 3 with haloalkynes in the presence of carbon monoxide gives α‐seleno‐substituted vinyl alkynyl ketones 5 in moderate yields. The reaction conditions are neutral and mild enough (room temperature, 1 atm carbon monoxide) that other functional groups in either coupling partner can be brought unaltered into the coupled product. The E geometry in the α‐alkylseleno vinylzirconocene reagent is maintained during the coupling reaction. © 2000 John Wiley & Sons, Inc. Heteroatom Chem 11:91–93, 2000     

The twinned crystal structure of μ‐2,2′‐bipyrimidine‐1κ2N1,N1′:2κ2N3,N3′‐bis­{tris­[4,4,4‐trifluoro‐1‐(2‐thienyl)butane‐1,3‐dionato‐κ2O,O′]terbium(III)} ethyl acetate solvate

The title compound, [Tb₂(C₂₄H₁₂F₉O₆S₃)₂(C₈H₆N₄)]·C₄H₈O₂, has two terbium(III) centers bridged by the polyazine ligand 2,2′‐bipyrimidine (bpm), which is distorted from planarity by 7.0 (2)°. The terminal ligand 4,4,4‐trifluoro‐1‐(2‐thienyl)­butane‐1,3‐dione (tta) is bidentate, coordinating through the two O atoms, while the bridging ligand is bis‐bidentate, coordinating through four equivalent N atoms. Both the complex and the ethyl acetate solvent mol­ecules are dis­ordered. The structure was refined as a non‐merohedral twin.     

Synthesis and characterization of new trifluoromethyl substituted 3‐ethoxycarbonyl‐ and 3‐pyrimidin‐2‐yl)‐(1,2,3)‐oxathiazinane‐S‐oxides

This paper describes the synthesis and characterization of a new series of 4‐substituted‐3‐ethoxycarbonyl‐6‐trifluoromethyl‐(1,2,3)‐oxathiazinane‐S‐oxides and 3‐(4,6‐diphenyl‐pyrimidin‐2‐yl)‐6‐trifluoromethyl‐(1,2,3)oxathiazinane‐S‐oxides from the cyclization reaction of 4,4,4‐trifluoro‐3‐hydroxybutylcarbamates and 4‐(4,6‐diphenyl‐pyrimidin‐2‐ylamino)‐1,1,1‐trifluoro‐butan‐2‐ols with thionyl chloride. The analysis of the NMR data allowed us to define important features of the molecular structure. Significant chemical and structural differences were observed between the trifluoromethylated oxathiazinanes obtained in this work from other analogue compounds reported in the literature.     

A Cinchona Alkaloid‐Functionalized Mesostructured Silica for Construction of Enriched Chiral β‐Trifluoromethyl‐β‐Hydroxy Ketones over An Epoxidation‐Relay Reduction Process

A cinchona alkaloid‐functionalized heterogeneous catalyst is prepared through a thiol‐ene click reaction of chiral N‐(3,5‐ditrifluoromethylbenzyl)quininium bromide and a mesostructured silica, which is obtained by co‐condensation of 1,2‐bis(triethoxysilyl)ethane and 3‐(triethoxysilyl)propane‐1‐thiol. Structural analyses and characterizations disclose its well‐defined chiral single‐site active center, and electron microscopy images reveal its monodisperse property. As a heterogenous catalyst, it enables an efficient asymmetric epoxidation of achiral β‐trifluoromethyl‐β,β‐disubstituted enones, the obtained chiral products can then be converted easily into enriched chiral β‐trifluoromethyl‐β‐hydroxy ketones through a sequential epoxidation‐relay reduction process. Furthermore, such a heterogeneous catalyst can be recovered conveniently and reused in asymmetric epoxidation of 4,4,4‐trifluoro‐1,3‐diphenylbut‐2‐enone, showing an attractive feature in a practical construction of enriched chiral β‐CF₃‐substituted molecules.     

Synthesis of 3‐substituted 2‐trifluoro(trichloro)methyl‐2H‐chromenes by reaction of salicylaldehydes with activated trihalomethyl alkenes

The reaction of activated trihalome‐ thylsubstituted alkenes with salicylaldehydes in the presence of triethylamine gives 3‐substituted 2‐trifluo‐ romethylchroman‐4‐ols and 2‐trifluoro(trichloro)methyl‐2H‐chromenes in high yields. © 2005 Wiley Periodicals, Inc. Heteroatom Chem 16:492–496, 2005; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/hc.20146     

Haloacetylated enol ethers: 15. Study of the regiochemistry of the cyclo‐condensation of β‐alkoxyvinyl trihalomethyl ketones with N‐methyl thiourea

A study of the regiochemistry of the cyclo‐condensation reaction of ß‐alkoxyvinyl trihalomethyl ketones with an unsymmetric dinucleophile N‐methyl thiourea to afford a series of 1‐methyl‐3‐(4,4,4‐trifluoro[chloro]‐3‐oxo‐1‐butenyl)thioureas and the corresponding N‐methyl pyrimidinethione derivatives is reported. The absolute assignment of the position of the N‐methyl group in the pyrimidine ring was obtained through a nmr study based on two dimensional HMBC and NOESY experiments.     

Room‐temperature Suzuki–Miyaura cross‐coupling reaction with α‐diimine Pd(II) catalysts

An α‐diimine Pd(II) complex containing chiral sec‐phenethyl groups, {bis[N,N′‐(4‐methyl‐2‐sec‐phenethylphenyl)imino]‐2,3‐butadiene}dichloropalladium (rac‐ C1 ), was synthesized and characterized. rac‐ C1 was applied as an efficient catalyst for the Suzuki–Miyaura cross‐coupling reaction between various aniline halides and arylboronic acid in PEG‐400–H₂O at room temperature. Among a series of aniline halides, rac‐ C1 did not catalyze the cross‐coupling of aniline chlorides and fluorides but efficiently catalyzed the cross‐coupling of aniline bromides and iodides with phenylboronic acid. The catalytic activity reduced slightly with increasing steric hindrance of the aniline bromides. The complexes {bis[N,N′‐(4‐fluoro‐2,6‐diphenylphenyl)imino]‐2,3‐butadiene}dichloropalladium and {bis[N,N′‐(4‐fluoro‐2,6‐diphenylphenyl)imino]acenaphthene}dichloropalladium were also found to be efficient catalysts for the reaction. Copyright © 2015 John Wiley & Sons, Ltd.     

Synthesis and Herbicidal Activity of Novel N‐(2‐Fluoro‐5(3‐methyl‐2,6‐dioxo‐4‐(trifluoromethyl)‐2,3‐dihydro‐pyrimidin‐1(6H)‐yl)phenyl)‐2‐phenoxyacetamide Derivatives

Thirteen novel N‐(2‐fluoro‐5‐(3‐methyl‐2,6‐dioxo‐4‐(trifluoromethyl)‐2,3‐dihydropyrimidin‐1(6H)‐yl)phenyl)‐2‐phenoxy)acetamides were designed and synthesized utilizing 4‐fluoro‐aniline and ethyl 3‐amino‐4,4,4‐trifluoro‐but‐2‐enoate as starting materials. The chemical structures of all compounds were confirmed by ¹H NMR, IR, mass spectrum and elemental analyses. Subsequently, the herbicidal activities of the as‐prepared compounds were evaluated in the greenhouse. Bioassay results indicated that most of compounds had better herbicidal activities against dicotyledonous weeds. Among all the tested compounds, compounds 4a – 4i showed good herbicidal activities at both pre‐emergence and post‐emergence treatment against two or three kinds of dicotyledonous weeds, such as Abutilon theophrasti Medic, Amaranthus ascendens L, and Chenopodium album L at the dosage of 75 g ai/ha.     

A new route to 5‐trifluoromethyl‐2,3‐dihydro‐1,4‐diazepine and 2‐trifluoromethylbenzimidazole

Ethylenediamine reacted readily with 4‐ethoxy‐1,1,1‐trifluoro‐3‐butene‐2‐one to form 5‐trifliuoromethyl‐2,3‐dihydro‐1,4‐diazepine in good yield. Under the same reaction conditions, o‐phenylenediamine gave 2‐trifluoromethylbenzimidazole and benzimidazole. © 2000 John Wiley & Sons, Inc. Heteroatom Chem 11:27–30, 2000     

(Thiocarbonyl‐α‐thio)carboxylic acid derivatives as transfer agents in reversible addition–fragmentation chain‐transfer polymerizations

Ethyl S‐(thiobenzoyl)thioacetate, ethyl S‐thiobenzoyl‐2‐thiopropionate, and S‐(thiobenzoyl)thioglycolic acid were used as chain‐transfer agents for the reversible addition–fragmentation chain‐transfer (RAFT) polymerizations of styrene, methyl methacrylate, and butyl acrylate. Of these polymerizations, only those of styrene and butyl acrylate with any of the transfer agents showed molecular weight control corresponding to controlled/living polymerizations. The best molecular weight control was observed for the polymerizations of styrene and butyl acrylate with ethyl (S)‐thiobenzoyl‐2‐thiopropionate. Semiempirical PM3 calculations were performed for the investigation of the relative heats of reaction of the chain‐transfer equilibria between the aforementioned chain‐transfer agents and dimer radicals of the three monomers. The molecular weight control of the polymerizations correlated with the stability trend of the leaving‐group radical of the chain‐transfer agent. This relatively simple computational model offered some value in determining which transfer agents would show the best molecular weight control in RAFT polymerizations. © 2002 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 40: 555–563, 2002; DOI 10.1002/pola.10143     

A convenient synthesis of substituted 3‐alkoxycarbonyl‐β,γ‐unsaturated esters with predominant Z‐selectivity

The consecutive reaction of bis[2,2,2‐trifluoroethyl]phosphite with sodium hydride, dimethyl maleate, and aldehydes gives 3‐alkoxycarbonyl‐β,γ‐unsaturated esters with predominant Z‐selectivity in 62–94% yields (Z/E = 85–60:15–40). The Z‐ and E‐isomer can be separated conveniently by column chromatography. © 2003 Wiley Periodicals, Inc. Heteroatom Chem 14:276–279, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/hc.10142     

Convenient One‐Pot Room Temperature Synthesis of 2‐(trifluoromethyl)‐1,2,3,4,7,8‐hexahydroquinolin‐5(6H)‐one derivatives via Catalyst‐Free Multicomponent Reactions

This paper describes an efficient approach for the synthesis of 2‐(trifluoromethyl)‐1,2,3,4,7,8‐hexahydroquinolin‐5(6H)‐one derivatives via a one‐pot four‐component reaction of aromatic aldehyde, 5,5‐dimethylcyclohexane‐1,3‐dione, 4,4,4‐trifluoro‐1‐(thien‐2‐yl)butane‐1,3‐dione, and NH₄OAc with excellent yields at room temperature. In this synthesis, the trifluoromethyl was efficiently introduced in hexahydroquinoline structure, and they may be valuable the drug candidates. This approach also offered several other advantages, such as catalyst‐free, mild conditions, and simple experimental operation.     

A Direct,Concise, and Enantioselective Synthesis of 2‐Substituted 4,4,4‐Trifluorobutane‐1,3‐diols Based on the Organocatalytic In Situ Generation of Unstable Trifluoroacetaldehyde

A direct, concise, and enantioselective synthesis of 2‐substituted 4,4,4‐trifluorobutane‐1,3‐diols based on the organocatalytic asymmetric direct aldol reaction of an ethyl hemiacetal of trifluoroacetaldehyde with various aldehydes was examined. A catalytic amount (30 mol %) of commercially available and inexpensive l ‐prolinamide is quite effective as an organocatalyst for the catalytic in situ generation of gaseous and unstable trifluoroacetaldehyde from its hemiacetal, and a successive asymmetric direct aldol reaction with various aldehydes in dichloromethane at 0 °C, followed by reduction with sodium borohydride, gives 2‐substituted 4,4,4‐trifluorobutane‐1,3‐diols in moderate to good yields (31–84 %) with low diastereoselectivities and good to excellent enantioselectivities (64–97 % ee).     

Stereoselective synthesis of (2E) 3‐amino‐2‐(1H‐benzimidazol‐2‐yl)acrylate and symmetric bisacrylates by transamination reactions

A range of various amines 2(a–i) was tested in transamination reactions using ethyl 2‐(1H‐benzimidazol‐2‐yl)‐3‐dimethylamino‐acrylate 1a. The (E)‐s‐cis/trans conformation of some representative products 4 was analyzed by ¹H and ¹³C NMR spectra. The C‐2/C‐3 bond of the compounds 3(a–i) is strongly polarized by a push‐pull effect. In the same manner, reactions of ethyl 2‐(benzoxazol‐2‐yl)‐3‐dimethylamino‐acrylate 1c with 1,4‐diaminobenzene 2i, ethylenediamine 2i, and 1,5‐diaminomaphthalene 2k have been investigated and gave directly the corresponding symmetric bis‐acrylates 4(a–c) in good yields. © 1999 John Wiley & Sons, Inc. Heteroatom Chem 10: 446–454, 1999     

A facile stereoselective synthesis of (E)‐α‐silylvinyl sulfides via hydromagnesiation of alkynylsilanes

Hydromagnesiation of alkynylsilanes 1 in diethyl ether gave (Z)‐α‐silylvinyl Grignard reagents 2 , which reacted with arylsulfenyl chlorides 3 to afford stereoselectively (E)‐α‐silylvinyl sulfides 4 in good yields. (E)‐α‐Silylvinyl sulfides 4 could undergo the cross‐coupling reactions with Grignard reagents in the presence of NiCl₂(PPh₃)₂ to give stereoselectively (Z)‐1,2‐disubstituted vinylsilanes 5 . © 2005 Wiley Periodicals, Inc. Heteroatom Chem 16:644–647, 2005; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/hc.20165     

Regioselective synthesis of 1,2,4‐triazol‐3(2H)‐ones and their 3(2H)‐thiones: Kinetic studies and selective pyrolytic deprotection

Selective pyrolytic deprotection of 2‐ethyl and 2‐cyanoethyl‐4‐arylidenimino‐1,2,4‐triazol‐3(2H)‐ones and their 3(2H)‐thiones was studied by flash vacuum pyrolysis. This study is useful in regioselective synthesis of 2‐ and 4‐substituted 1,2,4‐triazoles of potential biological applications. The kinetic results and product analysis lend support to a reaction pathway involving a six‐membered transition state. © 2003 Wiley Periodicals, Inc. Heteroatom Chem 14:50–55, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/hc.10086