This paper reports a study of the synthesis of aryltri-n-butylstannanes via a sonochemical Barbier reaction of aryl- and heteroaryl bromides with bis(tri-n-butyltin) oxide (2) in THF. Our results ...demonstrate that, despite previous reports on contrary, the aryltributylstannanes can also be obtained under the same reaction conditions via sonicated reactions between aryl monobromides and tri-nbutyltin chloride (2). A comparative study of the reactions of electrophiles 2 and 3 with bromobenzene, 2-bromopyridin, o- and m-bromoanisole, m-bromotoluene, 9-bromophenthrene, and 9-bromoanthracene, indicates that the corresponding aryl- and heteroaryl-tri-n-butylstannyl derivatives are obtained in about the same yields. Best reaction conditions and the results obtained in the investigation of the sonicated reactions between several aromatic and heteroaromatic dibromides are also reported. It was found that the reactions using 1,2-, 1,3-, and 1,4-dibromobenzenes, 4,4′-dibromobiphenyl, 1,4-dibromonaphthalene, 2,5- and 3,5-dibromopyridines, and 2,5-dibromothiophene lead to the corresponding bis(tri-n-butylstannylated) derivatives in many cases in very high yields. Also the excellent results obtained in the sonicated reactions of 1,3,5-tribromobenzene with 2 and 3 are reported.
The best reaction conditions and the syntheses of some new bis(tri-n-butylstannylated) aromatic and heteroaromatic compounds by means of a Barbier-like sonochemical reaction are reported. Full 1H-, 13C-, and 119Sn NMR data of the new organotin compounds are informed. Display omitted
•Synthesis of new aryl- and heteroaryl bis(tri-n-butylstannylated) compounds.•Sonochemical Barbier-like synthesis of bis(tri-n-butylstannylated) aromatic compounds mediated by Mg.•Use of bis(tri-n-butyltin) oxide and tri-n-butyltin chloride electrophiles for the synthesis of aryl tri-n-butyltin compounds.
New ternary silver(I) thiosaccharinates with pyridine and 1,10-phenanthroline are prepared and structurally characterized. The pyridine derivative is a dinuclear silver complex, Ag
2(tsac)
2py, with ...argentophilic interaction and very unusual metal environments. One Ag(I) is coordinated by two S atoms and the other silver atom by three N atoms.
Treatment of Ag
6(tsac)
6 (tsac
=
thiosaccharinate anion) with pyridine (py) and 1,10-phenanthroline (
o-phen) each affords two novel silver(I)-thiosaccharinate complexes: dinuclear Ag
2(tsac)
2py (
1) and polynuclear Ag(tsac)(
o-phen)
n
(
2). Both crystal structures have been determined by X-ray diffraction and spectroscopic structural analysis (IR and Raman, UV–Vis,
1H and
13C NMR) have also been made for both compounds. Thermal stability analysis (TGA and DTA) of complex
1 are used to confirm the strength of the pyridine coordination to the silver ion. The molecular structure of complex
1 shows some astonishing characteristics. The two silver atoms are in different environments: one of them is surrounded by two S atoms, while the other completes its coordination sphere by three N atoms, two from the thiosaccharinate anions and the third from a pyridine molecule. The short Ag(1)–Ag(2) contact distance, 2.9681(8)
Å, indicates an interaction between the two silver metal atoms exists. Complex
2 shows a thiosaccharinate molecule bridging two silver atoms through the exocyclic S atom while the
o-phenanthroline ligand is coordinated as a bidentate
N,
N chelate, forming a polynuclear chain. Quantum chemical calculations confirm the argentophilic character of the Ag–Ag interaction in complex
1, and its structure and vibrational assignments were correlated and confirmed theoretically.
We report here the results obtained in the study of organocatalytic asymmetric Diels–Alder reactions to optimize the synthesis of stereo defined allyltin derivatives using ...(Z)-2-(1-cyclohexenyl)-1-ethenyl(trineophyl)stannane (1) as diene and substituted dienophiles in the presence of (4R,5R)-α,α,α′,α′-tetraphenyl-1,3-dioxolane-4,5-dimethanol (TADDOL, I) and analogs (4R,5R)-α,α,α′,α′-tetra(1-naphtyl)-1,3-dioxolane-4,5-dimethanol (II) and (4R,5R)-α,α,α′,α′-tetra(9-phenantryl)1,3-dioxolane-4,5-dimethanol (III) as chiral catalysts to enhance stereoselectivity through hydrogen bond activation of the dienophile. Catalyst II provided excellent results and ultrasonic radiation at low temperature showed the shorter reaction times.
•Efficient organocatalytic asymmetric Diels–Alder reactions were studied in this work.•Stereo defined allyltin derivatives synthesized with excellent yields.•Excellent regio- and endoselectivity achieved.•TADDOL and TADDOL derivatives used as very efficient organocatalysts.
This paper reports the synthesis of dineophyltin dihydride (
3) following two procedures. The four steps synthesis starting from benzyl chloride and Sn was shown to be more convenient than the two ...step direct alkylation of SnCl
4. The study of the free radical hydrostannation of mono- and disubstituted acetylenes with hydride
3 shows that they are stereoselective and that the stereoisomers obtained in higher proportion are stable and easily separated by column chromatography. Some preliminary studies on the chemical reactivity of the new divinylsubstituted dineophyltin compounds in Stille reactions are also informed. Radical hydrostannatation of (E)-trisubstituted ethylenes with
3 did not succeed probably due to steric factors. The preparation of dineophyltin bromohydride (
27) is also reported. Radical addition of
27 to methyl (E)-2,3-disubstituted propenoates leads to mixtures of the corresponding erythro and threo adducts in diastereomeric excesses (d.e.) in the range of 74–90%.
The synthesis of dineophyltin dihydride (
3) and dineophyltin bromohydride (
27) is reported. Stereoselective free radical hydrostannation of mono- and disubstituted acetylenes with dihydride
3 and of methyl (E)-disubstituted propenoates with bromohydride (
27) are informed. Some preliminary studies on the chemical reactivity of the new divinylsubstituted dineophyltin compounds in Stille reactions are also reported.
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► Efficient synthesis of dineophyltin dihydride and dineophyltin bromohydride. ► Stereoselective radical hydrostannation of mono- and disubstituted alkynes. ► Regio- and stereocontrolled synthesis of divinyl stannanes. ► Reactivity of new divinyl stannanes. ► Stille reactions with new divinylsubstituted dineophyltin compounds.
The reaction of Ag6(tsac)6 (1) (tsac = thiosaccharinate anion) with triphenylphosphine gives rise to the already reported Ag(tsac)(PPh3)3 complex (2) and to two new silver‐thiosaccharinate‐phosphine ...complexes, Ag(tsac)(PPh3)2 (3) and Ag4(tsac)4(PPh3)4 (4) (PPh3= triphenylphosphine). Spectroscopic characterization was carried out using IR, UV‐Visible and NMR techniques and confirmed by single crystal X‐ray diffraction. In each complex a singular coordination mode for the thiosaccharinate ligand is observed. The most important features of the different coordination modes of the thionates are discussed. Compound 3 crystallizes in monoclinic system, space group Pn, with a = 11.2293(3) Å, b = 12.7282(3) Å, c = 13.6056(4) Å, β = 94.985(2)°, Z = 2; while crystals of compound 4 are monoclinic, space group P21/n, a = 15.024(3) Å, b = 14.681(3) Å, c = 21.914(4) Å, β = 95.31(3)°, Z = 2. The coordination around the silver atoms in both complexes consists of almost trigonal‐planar arrangements, AgP2S in 3 and AgS2P in 4.
The effect of bidentated phosphanes upon thiosaccharinate coordination in ternary silver and copper complexes is analyzed. Three solid silver and copper-diphosphanes complexes with thiosaccharinate ...as counter anion Ag(tsac)(dppe)(CH sub(3CN)) sub(n) ( 1), {Cu(tsac)(dppe)} sub(2( mu -dppe)) super(.)4CH sub(3CN ( 2) and Ag) sub(2)(tsac) sub(2(dppm)) sub(3) ( 3) (tsac: thiosacharinate anion, dppm: bis(diphenylphosphanyl)methane, dppe: bis(diphenylphosphanyl)ethane) were synthesized and fully characterized by means of spectroscopic techniques (FTIR, UV-Visible, and super(1H, ) super(3)1P and super(13CNMR). The crystal structures of complexes 1 and 2 were solved applying single crystal X-ray diffraction techniques. Complex 1 shows a 1-D polynuclear arrangement with dppe molecules bridging Ag(I) centers. Complex 2 is built by dinuclear units with two chelating and one bridging dppe molecules.)
Aim of this study is evaluating alteration of neuro-immune-endocrine parameters in exposed workers and estimating whether urban pollution can modify them.
Literature research. Different categories of ...exposed workers were included in the study (7287) and compared with controls (8054). To calculate results Effect Size (ES) and confidence interval were used.
A correlation between urban pollution exposition and some neurogenic mediators and metabolites alterations was demonstrated; blood values can be alterated by toxicity of benzene and by xenobiotic metabolites' mechanism; follicle stimulating hormone is significantly increased in exposed versus controls.
High heterogeneity and literature limitations, together with results of this meta analysis, induce to believe that is necessary to deepen the research about urban pollution effects on these parameters.
Free radical hydrostannation of methyl (
2) and (−)-menthyl (
3) (
E)-2,3-diphenylpropenoates and (
Z)-2,3-diphenylpropenenitrile with (−)-menthyldimethyltin hydride (
1) takes place with high ...diastereoselectivity. The observed 1,2-stereoinduction is explained taking into account that the combination of both allylic strain effects and the hyperconjugation existing between the β-trialkyltin substituent and the half filled carbon p orbital leads to particularly stable conformations in the intermediate radicals. These results, together with those reported earlier, indicate that it is possible to predict the stereochemistry of the hydrostannation products by considering the type of substituents attached to the olefinic bond and the preferred conformation of the intermediate radicals resulting from the addition of the organotin radical. These studies also demonstrate that it is possible to achieve asymmetric hydrostannations using organotin hydrides with chiral organic ligands. Full
1H-,
13C-, and
119Sn-NMR data of the new organotin adducts are given.
Aryltrialkyltin compounds react with borane in THF to give mixtures of trialkyltin hydrides and arylboranes, which on hydrolysis give arylboronic acid in high yields. The arylboronic acids are easily ...separated and obtained free of organotins.
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