Synthesis Of Trans Research Articles

Synthesis of tris( N, N′-dialkyldithiocarbamato) iron(III) complexes and their thermal decomposition studies by various techniques

Several complexes of the type [Fe(S 2CNR 1R 2) 3] with symmetrical (R 1 = R 2 = C 6H 5, C 6H 5CH 2, C 4H 8N and C 5H 10N) and unsymmetrical ligands (R 1 = CH 3, R 2 = C 6H 5 and n-C 4H 9; R 1 = C 2H 5, R 2 = C 6H 5 and n-C 4H 9) have been prepared and characterized by elemental analysis, infrared spectroscopy and magnetic measurements. Thermogravimetric studies of the complexes exhibit a prominent weight loss of ∼70% in the temperature range 200–350 °C. In most cases decomposition occurs in two stages though in some cases it also occurs in a single, two and three stages. Thermogravimetric studies and differential thermal analysis suggest the formation of iron sulphide as an intermediate but finally Fe 2O 3 is formed. Room temperature Mössbauer spectra exhibit an unsymmetrical doublet resolved into two quadrupole doublets corresponding to an equilibrium mixture of high and low spin states. Mössbauer spectra recorded after heating the samples at 250, 550 and 750 °C in air confirm the formation of iron sulphide and γ-Fe 2O 3 in a particular case as intermediate products though finally α-Fe 2O 3 is formed. The activation energy for the thermal decomposition varies between 61 and 198 kJ mol −1 and it is a first order reaction. It is suggested that intramolecular rearrangement may be taking place during decomposition.

Synthesis of Tris(tetrathiafulvaleno)dodecadehydro- [18]annulenes and Their Self-Assembly

[reaction: see text] Synthesis of electroactive tris(tetrathiafulvaleno)dodecadehydro[18]annulenes with ester substituents has been carried out with palladium-mediated cyclotrimerization of 4,5-diethynyl-TTFs. The TTF[18]annulenes produce stacked dimmers in solution and exhibit solvatochromism and thermochromism. The TTF[18]annulene-hexabutyl ester forms a molecular wire from an aqueous THF solution with cooperative S-S and pi-pi stacking interactions.

New Approaches to Synthesis of Tris[1,2,4]triazolo[1,3,5]triazines.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access the actual ChemInform Abstract, please click on HTML or PDF.

Synthesis of the first tris(crown formazan)

A synthesis of tris(crown formazan) 2 from the corresponding hexakis(acetamidophenoxymethyl)benzene 11 by hydrolysis with an ethanolic solution containing hydrochloric acid followed by diazotization and subsequent coupling with cyanoacetic acid in pyridine containing CuSO 4 is described.

First Synthesis of Trans- and Cis-Dendrochrysanines

Trans- and cis-dendrochrysanines (1 and 2), isolated from the stems of Dendrobium chrysanthum Wall., were first synthesized from L-proline. The absolute configuration of 1 and 2 was established to be S by the syntheses.

Synthesis of enantiomerically pure trans‐(1R,2R)‐ and cis‐(1S,2R)‐1‐amino‐2‐indanol by lipase and ω‐transaminase

Syntheses of trans-(1R,2R) and cis-(1S,2R)-1-amino-2-indanol (AI) were accomplished by a series of enantioselective enzymatic reactions using lipase and transaminase (TA). Lipase catalysed enantioselective hydrolysis of 2-acetoxyindanone was employed to prepare (R)-2-hydroxy indanone (HI). trans-AI (5 mM) (de > 98%) was produced from 20 mM (R)-2- HI using omega-TA and 50 mM (S)-1-aminoindan as an amino donor in water-saturated ethyl acetate. For the production of cis-AI, the diastereomeric (2R)-AI was synthesized from (R)-2-HI using reductive amination, and the kinetic resolution was performed with omega-TA. The enantioselectivity of omega-TA for (2R)-AI was increased to 22.1 in the presence of 5% gamma-cyclodextrin. cis-AI (15.4 mM) (96% de) was obtained from 40 mM (2R)-AI using 30 mM pyruvate and omega-TA (25 mg) in 10 mL of 100 mM phosphate buffer (pH 7.0).

Atom-Economic Synthesis of Tris[2-(organylthio)ethyl]phosphine Oxides from Phosphine and Vinyl Sulfides

Phosphine, generated from elemental phosphorus in the system KOH-toluene-H2O, reacts with vinyl sulfides under free radical conditions (AIBN, dioxane, 65–70°C, atmospheric pressure) to form regiospecifically tris[2-(organylthio)ethyl]phosphines, which are readily oxidized in air to corresponding tris[2-(organylthio)ethyl]phosphine oxides.

Synthesis of bithiophenesilane dendrimer of the first generation

The synthesis of tris{5′-[methylbis(2-thienyl)silyl]2,2′-bithienyl-5-yl} methylsilane, a first-generation bithiophenesilane dendrimer, is described. The conditions of effective formation of methyltrithienylsilane were found; methyltris(5-bromo-2-thienyl)silane and a number of other monofunctional derivatives of methyltrithienylsilane were synthesized for the first time. The advantages and drawbacks of the Suzuki and Kumada reactions for the formation of bithienyl fragments in the synthesis of oligothienylsilane dendrimers are discussed.

Bonding along a linear B...N...B triad.

The synthesis of tris(2,6-dihydroxyphenyl)amine diborate, 4, is reported. This compound contains a linear B...N...B array for which a symmetrical three-center two-electron (3c-2e) bond is possible. The X-ray crystal structure of 4 shows that 3c-2e bonding is, in fact, absent. Rather, the B-N-B array of 4 is unsymmetrical, having a 2c-2e B-N dative bond with the remaining boron pyramidalized outward and bonded to the oxygen of THF, i.e., 4 x THF. In THF solution, 4 displays temperature-dependent 13C NMR spectra from which a DeltaG++ of 11.6 kcal/mol at 262 K may be calculated. The dynamic process observed in solution corresponds to a bond-switching equilibrium in which the B-N bond oscillates between the two borons ("bell clapper"). Ab initio calculations indicate that the most likely pathway for the bond switch does not involve a 3c-2e B...N...B bond, but rather occurs by nucleophilic attack of THF on the datively bonded boron to generate 4 x (THF)2, lacking any B-N interactions, followed by loss of one THF. The B-N-B system of 4 sans the perturbing effect of solvent was also investigated computationally. The form of 4 containing a 3c-2e bond is found to be a transition state in the solvent-free bond-switch reaction of 4, lying 2.66 kcal/mol above 4. The stability of three-center bonds to in-line distortion (viz., X...Y...X --> X-Y.........X) is discussed from the point of view of the second-order Jahn-Teller effect.

Further study of tris(cyclohexyl)stannane compounds, Cy 3SnX. Syntheses of the compounds with X = Br, I, N 3 and NCS and redetermination of the crystal structures of Cy 3SnX (X = Br and I)

Methods of preparation and far IR data are presented for various Cy 3SnX compounds. The synthesis of tris(cyclohexyl)tin hydroxide, Cy 3SnOH, is also described. Redeterminations of the crystal structures of tris(cyclohexyl)tin bromide and iodide, Cy 3SnBr and Cy 3SnI, confirm their molecular nature and improve considerably upon the results reported earlier [S. Calogero, P. Ganis, V. Peruzzo, G. Tagliavini, G. Valle, J. Organomet. Chem. 220 (1981) 11] providing, in both cases, lower Rfactors and, in particular, a revised estimate of the Sn–I bond length, now 2.7463(6) Å.

Facile Synthesis of Tris(1-naphthylmethyl)phosphine Oxide: A Route to Design of Complexing Luminophores

Facile Synthesis of Tris(1-naphthylmethyl)phosphine Oxide: A Route to Design of Complexing Luminophores

A Comparison between Kinetic Parameters from the Synthesis of Tris(p-nitrophenyl)phosphite and Tris(p-nitrophenyl)phosphate Using Reaction Calorimetry

Tris(p-nitrophenyl)phosphite was prepared by a modification of a “one-pot” methodology developed for the preparation of triaryl phosphates. This exothermic reaction was performed in a Mettler RC-1 calorimeter. The principal aim of this work was to compare the reactivity of phosphorus trichloride and phosphorus oxychloride in their reactions with sodium p-nitrophenoxide. The reaction rate and the reaction rate constant for the synthesis of tris(p-nitrophenyl)phosphite were evaluated and compared to the obtained values for the tris(p-nitrophenyl)phosphate synthesis. Phosphorus trichloride was found to react faster than phosphorus oxychloride, but the reaction with the phosphorus oxychloride proved to be more exothermic.

Synthesis of trans-[RuCl 2(dppe) 2] using the tetraalkylammonium chloride under transfer phase catalysis conditions. Crystal structure of the novel trans-[RuBrCl(dppe) 2

The catalyst precursor trans-[RuCl 2(dppe) 2] has been synthesized by solid state reaction of RuCl 3 · 3H 2O with tetrabutylammonium chloride (TBAC) and subsequent coordination with 1,2-bis-(diphenylphosphine)ethane (dppe) in dichlromethane solution. Reaction time, yield, work up and cleanness were improved by this method when compared with classical procedures. Use of tetrabutylammonium bromide (TBAB) as catalyst has afforded a novel trans-[RuBrCl(dppe) 2] whose crystal structure was analyzed.

Design and Synthesis of Tris[bis(benzylammonium)aryl]phosphines with Bulky meta-Substituents.

Abstract A novel 3,5,3′,5′,3″,5″-hexakis(dimethylamino)methyl substituted triphenylphosphine analogue has been prepared. The six amine functionalities of the corresponding phosphine oxide and sulfide were alkylated quantitatively with methyl iodide and benzyl bromide, as well as with G1 and G2 Frechet dendrons to afford the respective hexa-ammonium triarylphosphine oxides and sulfides. The phosphine sulfide derivatives were deprotected with P(n-Bu)3 to afford a series of hexa-ammonium triarylphosphines that range from small molecules to first and second generation dendrimers (MW up to 5451.44). Upon formation of the hexa-ammonium salt a clear shift in 31P NMR is observed, indicative for opening of the C–P–C angle of the triaryl phosphine. Calculations on the hexacationic phosphines show an increased barrier of rotation around the P–C(aryl) bond with increasing size of the N-substituents. The calculated structure of the G2-dendron alkylated hexa-ammonium triarylphosphine shows that this dendritic phosphine has a disc-like rather than a cone-like structure, with an estimated cone angle of approximately 180°

A convenient preparative method for anionic tris(substituted pyrazolyl)methane ligands

The synthesis of tris[3-(6-carboxypyridin-2-yl)pyrazol-1-yl]methane is described in a linear multi-step protocol. The pyridyl-pyrazolyl arms are first constructed before being condensed with chloroform. Careful study of the condensation reaction shows the presence of an isomeric form of the tris(pyrazolyl)methane derivative in which one of the pyrazolyl substituents is linked through the nitrogen atom at the 2 position of the pyrazol. After acid-catalysed isomerisation to the desired isomer, the intermediate compound was subjected to a carboalkoxylation reaction and a subsequent hydrolysis. These are some rare examples of reactions directly occurring on the tris(pyrazolyl)methane platforms.

Design and synthesis of tris[bis(benzylammonium)aryl]phosphines with bulky meta-substituents

A novel 3,5,3′,5′,3″,5″-hexakis(dimethylamino)methyl substituted triphenylphosphine analogue has been prepared. The six amine functionalities of the corresponding phosphine oxide and sulfide were alkylated quantitatively with methyl iodide and benzyl bromide, as well as with G1 and G2 Fréchet dendrons to afford the respective hexa-ammonium triarylphosphine oxides and sulfides. The phosphine sulfide derivatives were deprotected with P( n-Bu) 3 to afford a series of hexa-ammonium triarylphosphines that range from small molecules to first and second generation dendrimers (MW up to 5451.44). Upon formation of the hexa-ammonium salt a clear shift in 31P NMR is observed, indicative for opening of the C–P–C angle of the triaryl phosphine. Calculations on the hexacationic phosphines show an increased barrier of rotation around the P–C(aryl) bond with increasing size of the N-substituents. The calculated structure of the G2-dendron alkylated hexa-ammonium triarylphosphine shows that this dendritic phosphine has a disc-like rather than a cone-like structure, with an estimated cone angle of approximately 180°

Synthesis of trans‐(3S)‐Amino‐(4R)‐alkyl‐ and ‐(4S)‐aryl‐piperidines via Ring‐Closing Metathesis Reaction.

AbstractFor Abstract see ChemInform Abstract in Full Text.

Novel proline hydroxylase activities in the pneumocandin-producing fungus Glarea lozoyensis responsible for the formation of trans 3- and trans 4-hydroxyproline.

Novel proline 3-hydroxylase (P3H) and proline 4-hydroxylase (P4H) activities that convert free l-proline to both trans 3- and trans 4-hydroxy- l-proline were detected in protein extracts of the anamorphic fungus Glarea lozoyensis. The enzymatic conversion of l-proline to trans 3- and trans 4-hydroxy- l-proline was strictly dependent on alpha-ketoglutarate, ascorbate, and dithiothreitol. Ferrous iron was required for optimal P3H and P4H activity. These substrate and co-factor requirements indicate these enzyme activities belong to the class of 2-oxoglutarate-dependent dioxygenases. Both P3H and P4H were inhibited by zinc and other trace metals. The addition of proline to the fermentation medium resulted in an increase in the specific activity of P4H and a decrease in the synthesis of pneumocandin C(0). Additionally, the synthesis of trans 3- and trans 4-hydroxy- l-proline in vivo was affected differently by the proline concentration in the medium. This result suggested that two enzymes may be responsible for the regio- and stereospecific hydroxylation of l-proline.

Lewis Acid Promoted Regio‐ and Stereoselective Hetero Nucleophilic Addition to a Piperidinyl Aziridine. Synthesis of trans 3‐Amino‐4‐substituted Piperidines.

AbstractFor Abstract see ChemInform Abstract in Full Text.

Syntheses of Bis(indolyl)‐Piperazine Alkaloids, Dragmacidin B and C, and Dihydrohamacanthin A.

AbstractFor Abstract see ChemInform Abstract in Full Text.