Synthesis and activity of two trifluorinated analogues of 1-deoxy-d-xylulose 5-phosphate

An improved synthesis of 1,1,1-trifluoro-1-deoxy-d-xylulose 5-phosphate and an access to the reduced diastereomer mixture analogues 1,1,1-trifluoro-1-deoxy-d-xylitol 5-phosphate and 1,1,1-trifluoro-1-deoxy-d-lyxitol 5-phosphate are described. Inhibitor activity of all compounds on the MEP pathway for isoprenoid biosynthesis was evaluated.     

Synthesis, structure and complexation of the fluorinated 1,3-enaminoketones containing at the nitrogen atom substituents with a terminal C≡C bond

The reaction of fluorinated lithium 1,3-diketonates with propargylamine hydrochloride and 1,1,1-trifluorpentane-2,4-dione or 1,1,1-trifluoro-4-methoxypent-3-en-2-one with propargylamine and 3-aminophenylacetylene were performed to obtain fluorinated 1,3-enaminones containing at a nitrogen atom substituents with terminal C≡C bonds: (Z)-1,1,1-trifluoro-4-(2-propynylamino)-3-pentene-2-one, (Z)-1,1,2,2-tetrafluoro-5-(2-propynylamino)-4-hexen-3-one, and 4-(3-ethynylphenylamino)-1,1,1-trifluoropentyl-3-en-2-one. Reactions of 4-(3-ethynyl-phenylamino)-1,1,1-trifluoro-pentyl-3-en-2-one with Cu(II) acetate or nanosized powder of copper or its oxides led to the respective chelate complex. The structure of (Z)-1,1,2,2-tetrafluoro-5-(2-propynylamino)-4-hexen-3-one and a copper complex of 4-(3-etinilphenylamino)-1,1,1-trifluoropenta-3-en-2-one was determined by XRD.     

CH stretching vibrational overtone spectra of 1,3,5,7-cyclooctatetraene and 1,1,1-trichloroethane

Local mode frequencies, omega, and anharmonicities, omegax, are obtained from the delta upsilon(CH) = 2-7 spectral regions of 1,3,5,7-cyclooctatetraene (COT) and 1,1,1-trichloroethane. In 1,1,1-trichloroethane omega and omega x are used in conjunction with ab initio potential energy surfaces to calculate local mode anharmonicity-torsion coupling terms, delta(omega x), and frequency-torsion coupling terms, delta(omega). Blue-shifting of sterically hindered CH oscillators in 1,1,1-trichloroethane indicates nonbonded, through-space intramolecular interactions with Cl. Multiple, complex Fermi resonances are observed in 1,1,1-trichloroethane and in COT between local mode states and local mode/normal mode combination states. Intensities of vibrational overtone transitions are calculated in the range delta upsilon(CH) = 3-9 using ab initio dipole moment functions and the harmonically coupled anharmonic oscillator (HCAO) model. HCAO intensities are compared to experimental intensities at delta upsilon(CH) = 3.     

New trigonal tris(phosphine oxides)

The reaction of 1,1,1-tris(chloromethyl)propane with diphenylphosphine under phase-transfer conditions afforded 1,1,1-tris(diphenylphosphinomethyl)propane, whose oxidation gave a previously unknown representative of trigonal tris(phosphine oxides), viz., stable 1,1,1-tris(diphenylphosphorylmethyl)propane. Its analogs, viz., bis(diphenylphosphoryl)diphenylphosphinomethane and tris(diphenylphosphoryl)methane, are unstable in air and decompose with the cleavage of the P-C bond.Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 9, pp. 1926–1929, September, 2004.     

Synthesis and hydrogenation of (E)-γ-aryl-γ-morpholino-α-trifluoromethylated allyl alcohols through the reaction of trifluoroacetaldehyde ethyl hemiacetal with enamines

Treatment of trifluoroacetaldehyde ethyl hemiacetal with enamines, derived from acetophenone derivatives, at room temperature gave (E)-1,1,1-trifluoro-4-morpholino-4-aryl-but-3-en-2-ols, which are intermediates for preparation of the β-trifluoromethylated aldol products, 4,4,4-trifluoro-3-hydroxy-1-aryl-butan-1-ones. The structure of the intermediate (E)-1,1,1-trifluoro-4-morpholino-4-(4-nitrophenyl)-but-3-en-2-ols could be assigned by ¹H, ¹³C NMR, IR, and X-ray crystallography. Furthermore, hydrogenation and reductive deamination of the intermediate (E)-1,1,1-trifluoro-4-morpholino-4-aryl-but-3-en-2-ols with hydrogen in the presence of a catalytic amount (10 mol %) of palladium on carbon in trifluoroethanol proceeded smoothly at room temperature to give 1,1,1-trifluoro-4-aryl-2-butanols in good to excellent yields.     

Copper‐Catalyzed Triboration: Straightforward,Atom‐Economical Synthesis of 1,1,1‐Triborylalkanes from Terminal Alkynes and HBpin

A convenient and efficient one‐step synthesis of 1,1,1‐triborylalkanes was achieved via sequential dehydrogenative borylation and double hydroborations of terminal alkynes with HBpin (HBpin=pinacolborane) catalyzed by inexpensive and readily available Cu(OAc)₂. This process proceeds under mild conditions, furnishing 1,1,1‐tris(boronates) with wide substrate scope, excellent selectivity, and good functional‐group tolerance, and is applicable to gram‐scale synthesis without loss of yield. The 1,1,1‐triborylalkanes can be used in the preparation of α‐vinylboronates and borylated cyclic compounds, which are valuable but previously rare compounds. Different alkyl groups can be introduced stepwise via base‐mediated deborylative alkylation to produce racemic tertiary alkyl boronates, which can be readily transformed into useful tertiary alcohols.     

Regioselective [3+3] Cyclization of 1,3‐Bis(silyloxy)buta‐1,3‐dienes with 1,1,1‐Trifluoro‐4‐(silyloxy)alk‐3‐en‐2‐ones: New and Convenient Synthesis of Functionalized 5‐Alkyl‐3‐(trifluoromethyl)phenols

Functionalized 5‐alkyl‐3‐(trifluoromethyl)phenols were prepared by formal [3+3] cyclization of 1,3‐bis(silyloxy)buta‐1,3‐dienes with 1,1,1‐trifluoro‐4‐(silyloxy)alk‐3‐en‐2‐ones derived from 1,1,1‐trifluoroalkane‐2,4‐diones. The latter were prepared by condensation of the dianion of 1,1,1‐trifluoropentane‐2,4‐dione with alkyl halides.     

Enumeration of Isomers of Alkylcyclobutadienes by Means of Alkyl 1,1,1-Triradicals

Previous studies have shown that alkyl 1,1-biradicals could be used to enumerate the constitutional isomers of alkenes [1] and cyclopropanes [2]. In this study, an algorithm of using alkyl 1,1,1-triradicals to enumerate the constitutional isomers of alkylcyclobutadienes is described. An alkylcyclobutadiene molecule is considered to be formed by four alkyl 1,1,1-triradicals by pairing two of the electrons with two of the adjacent alkyl 1,1,1-triradicals, and the remaining unpaired electron with one of the other adjacent alkyl 1,1,1-triradical. This enumeration algorithm showed that the constitutional isomers of the methanol series enumerated by Henze and Blair [3] can be used for enumerating the constitutional isomer of unsaturated cyclic compounds.     

The synthesis of 3H-1,2,4-thiadiazolo[3,4-b]benzothiazoles

2-Aminobenzothiazole reacted with 1,1,1-trichloromethanesulfenyl chloride yielding 1,1,1-trichloro-N-(2-benzothiazolyl)methanesulfenamide. Subsequent cyclization using either aromatic or heteroaromatic amines readily yielded derivatives of the 3H-1,2,4-thiadiazolo[3,4-b]benzothiazole ring system. Spectral data and brominations of these benzothiazoles are described.     

Time trends of 1,1,1-trichloroethane, trichloroethylene, and perchloroethylene in confined and unconfined aquifers of a groundwater system in northern Italy

The concentrations of 1,1,1-trichloroethane, trichloroethylene, and perchloroethylene were recorded in a groundwater system of Northern Italy over the period 1985-1997. In the unconfined recharging aquifer these chemicals showed a remarkable overall decline which was accompanied by a five-fold reduction in their consumption (from approx. 250 to approx. 50 tons year-1) over the same period. The time trends for the confined aquifers indicated a steady decline for 1,1,1-trichloroethane which was accompanied by a constant concentration of trichloroethylene and an increasing presence of perchloroethylene. It is suggested that the confined aquifers are recording a contamination which took place in the unconfined recharging aquifer before monitoring period (1982) started. At present, in most of the study area 1,1,1-trichloroethane contamination is below the detection limit (0.1 microgram/L). For trichloroethylene and perchloroethylene, the average unconfined aquifer contamination accounts for approx. 1 +/- 1 and approx. 4 +/- 3 micrograms/L, respectively, while in the confined aquifers the average concentrations are approx. 8 +/- 3 and approx. 35 +/- 5 micrograms/L, respectively.     

1,1,1-and 1,1,3-trihalo-2-sulfanylpropan-2-ols: New preparatively accessible synthons

A procedure has been developed for the synthesis of 1,1,1-trichloro-2-sulfanylpropan-2-ol and 1,1,3-tribromo-2-sulfanylpropan-2-ol via acid-catalyzed addition of hydrogen sulfide to the corresponding ketones. The stability of the resulting hydroxy thiols was estimated by analyzing the potential energy surface for the reaction of 1,1,1-trichloropropan-2-one with hydrogen sulfide in the presence of hydrogen chloride. In addition, quantum-chemical analysis of rotational isomerism of 1,1,1-trichloro-2-sulfanylpropan-2-ol was performed.     

4-Halogeno-1,1,1-trifluorobut-3-yn-2-one [4+2] cycloadducts and their cross-coupling with organozinc compounds

The reactions of 4-chloro-1,1,1-trifluorobut-3-yn-2-one and 4-bromo-1,1,1-trifluorobut-3-yn-2-one with conjugated dienes afford [4+2] cycloadducts in high yields. The halogen atom in the products is readily replaced by a (het)aryl residue in the cross-coupling with organozinc compounds.     

Synthesis of trifluoromethyl-substituted salicylates by cyclocondensation of 1,3-bis(silyloxy)-1,3-butadienes with 4,4-dimethylthio-1,1,1-trifluorobut-3-en-2-one

A formal [3+3] cyclocondensation of 1,3-bis(silyl enol ethers) with the little-known 4,4-dimethylthio-1,1,1-trifluorobut-3-en-2-one was studied. In contrast to 4,4-dimethoxy-1,1,1-trifluorobut-3-en-2-one, this α-oxoketene dithioacetal reacts with 1,3-bis(trimethylsilyloxy)-1,3-butadienes in the presence of TiCl₄ to give mainly 6-methylthio-4-(trifluoromethyl)salicylates via 1,2-addition. The scope and limitations of the reaction are discussed.     

Fluorine-Containing Organozinc Reagents Part 1 A Simple Synthesis of 2,2-Dichloro-3,3,3-trifluoropropanol

The title compound 1 , which can be regarded as a synthetic equivalent of substituted 1,1,1-trifluoroacetone 2 , is prepared by Zn-induced reductive addition of 1,1,1-trichloro-2,2,2-trifluoroethane ( 3 ) to formaldehyde ( 4 ). A brief survey of the scope of this C? C-bond formation leading to a variety of new CF₃-containing synthetic building blocks is also given.     

Transport of liquids in barrier plastics

The transport of 1,1,2-trichloroethane, 1,1,2-trichloroethylene, and 1,1,1-trichloroethane in the high nitrile polymer Barex® 210 has been characterized as a function of temperature, polymer moisture content, polymer morphology, film thickness, and composition of liquid mixtures. The characterization studies were conducted using a novel liquid sorption procedure and a new variable temperature liquid permeation instrument. Although the liquids are structurally similar, they exhibit remarkably different transport behavior. 1,1,2-Trichloroethane is a strong penetrant, 1,1,2-trichloroethylene is a weak penetrant, and 1,1,1-trichtoroethane is nearly a non-penetrant for Barex® 210. The results obtained in this study are useful in evaluating transport mechanisms and provide guidance in designing procedures for evaluating barrier plastics as packaging materials for liquid products.     

2-Chloro-1,1,1-Triethoxyethane and its Use in a Versatile Synthesis of Substituted, 2-Chloromethyl Heterocycles Including Benzothiazole and Benzoxazole

An efficient procedure suitable for large scale preparation of 2-chloro-1,1,1-triethoxyethane and its use in a versatile synthesis of 2-chloromethyl derivatives of an assortment of heterocycles are described.     

Recent advances in the anionic synthesis of chain-end functionalized polymers

Recent results for the preparation of chain-end functionalized polymers using alkyllithium-initiated anionic polymerization are described. Termination with 4-chloro-1,1,1-trimethoxybutane has been used to prepare trimethoxy ortho ester (carboxyl)-functionalized polymers. Functionalization with the oxiranes, glycidoxypropyltrimethoxysilane, 3,4-epoxy-1-butene and 1,1,1-trifluoro-2,3-epoxypropane, has been investigated to prepare trimethoxysilyl-functionalized polymers, 1,3-diene-functionalized macro monomers and trifluoromethyl-functionalized polymers, respectively. Secondary amine-functionalized polymers have been prepared by termination with N-(benzylidene)methylamine and also using an N-benzyl tertiary amine-functionalized alkyllithium initiator followed by hydrogenolysis of the benzyl group.     

New synthesis of trifluorinated amines from 1-bromopropargylic amines in superacid

Treatment of 1-bromopropargylic amines affords the corresponding 1,1,1-trifluoro in one step in HF-SbF₅ medium. 1-Bromo-1,1-difluoro or 2-bromo-1,1,1-trifluoro derivatives could also be prepared, depending on the reaction conditions.     

Is there any three-center CBC bond in 1, 5-C2B3H5 and 1,5-C2B3H3?

Localized molecular orbitals, two- and three-center bond indices of 1,5-dicarba-closo-pentaborane ( 5 ) and 1,5-dicarba-closo-pentaborane ( 3 ) and their hydrocarbon analogs bicyclo [1,1,1]-pentane and [1,1,1] propellane, respectively, have been calculated using a suitable basis set. No previously reported three-center CBC bond has been found. However, a new three-center BCB bond has been observed in 1,5-dicarba-closo-pentaborane ( 5 ). © 1995 John Wiley & Sons, Inc.     

Amidrazones. 8. Synthesis of 1,2,4-oxdiazoles by thermolysis of N3-acylamidrazone ylides

N³-Acylamidrazone ylides 3 were synthesized by the reaction of 2-(iminophenylmethyl)-1,1,1-trimethylhydrazinium hydroxide, inner salt ( 2a ) or 2-(1-iminoethyl)-1,1,1-trimethylhydrazinium hydroxide, inner salt ( 2b ) with acyl chlorides or acetic anhydride. Thermolysis of 3 gave 3,5-disubstituted oxadiazoles 4 and trimethylamine.