Preparation of Triethylammonium Tetra-Arylborates (TEATABs): Coupling Partners for the Suzuki Reaction

Kuuloja, Noora; Kylmälä, Tuula; Tois, Jan; Sjöholm, Rainer; Franzén, Robert

doi:10.1080/00397911003718086

Cited by 11 publications

(7 citation statements)

References 28 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Salt metathesis of the recently reported titanium chlorido complex [TiCl(Xy‐N 3 N)] (Xy‐N 3 N=[{(3,5‐Me 2 C 6 H 3 )NCH 2 CH 2 } 3 N] 3− ) with alkali borate salts did not selectively afford the expected titanium cations . However, protonolysis of the corresponding titanium alkyl complex [Ti(CH 2 SiMe 3 )(Xy‐N 3 N)] ( 1‐CH 2 SiMe 3 ) with the Brønsted acid [NEt 3 H][B(3,5‐Cl 2 C 6 H 3 ) 4 ] or with [PhNMe 2 H][B(C 6 F 5 ) 4 ] in chlorobenzene under ambient conditions selectively gave the titanium(IV) cations [Ti(Xy‐N 3 N)][B(3,5‐Cl 2 C 6 H 3 ) 4 ] ( 1[B(Ar Cl ) 4 ] ; B(Ar Cl ) 4 = tetrakis(3,5‐dichlorophenyl)borate) or [Ti(Xy‐N 3 N)][B(C 6 F 5 ) 4 ] ( 1[B(Ar F ) 4 ] ), which were isolated as red solids in 76 and 55 % yield, respectively (Scheme ). Under complete exclusion of air, both complexes are stable at ambient temperature for an indefinite period of time in non‐coordinating solvents, such as chlorobenzene or dichloromethane, but immediately react with coordinating solvents, such as THF or Et 2 O.…”

Section: Resultscontrasting

confidence: 99%

“…Salt metathesis of the recently reported titaniumchlorido complex [TiCl(Xy-N 3 N)] (Xy-N 3 N = [{(3,5-Me 2 C 6 H 3 )NCH 2 CH 2 } 3 N] 3À ) with alkali borate salts did not selectively afford the expected titaniumc ations. [6] [7] or with [PhNMe 2 H][B(C 6 F 5 ) 4 ] [8] in chlorobenzeneu nder ambient conditions selectively gave the titanium(IV) cations (3,5- 4 ] (X = Cl, F) were fully characterizedb y means of multinuclear NMR spectroscopy and elementala nalysis (see Sections 2.1 and 2.2 in the Supporting Information). Single-crystal XRD reveals that both cations are isostructural and well separated from the borate anions( Figure 1a nd Figure S35 in the Supporting Information).…”

Section: Resultsmentioning

confidence: 99%

“…This reactionc an be considered as an ucleophilic substitution ato ne of the a-carbon atoms of THF, which can be activated by other acids, including ap roton. Lewis base induced ring openingo fT HF at Lewis acidic (2),T i1ÀN2 1.933(2), Ti1À N3 1.911(2), Ti1ÀN4 2.219(2), Ti1ÀO1 2.058(2), Ti1···C1 2.932(2), Ti1···C11 2.950(2),T i1···C212.886(2);O1-Ti1-N41 70.96 (6), N1-Ti1-N4 75.89 (7), N2-Ti1-N4 76.04 (7), N3-Ti1-N4 76.81 (7). Group 4m etal centers is also aw ell-known reaction.…”

Section: Resultsmentioning

confidence: 99%

“…Molecular structure of 4b in the solid state with displacement parameters at the 50 %p robability level. Hydrogen atoms are omittedf or clarity.S electedi nteratomic distances []and angles [8]: Ti1ÀN1 2.094(5), Ti1ÀN2 1.906 (5), Ti1ÀN3 1.942(4), Ti1ÀN4 2.275(4), Ti1ÀN5 1.858 (5),N 1 ÀC9 1.317 (7), N2ÀC19 1.442 (7), N3ÀC29 1.458 (7),C 9 ÀC101.474(9), C19ÀC20 1.500(9),C 29À C30 1.509 (6);N4-Ti1-N51 68.88(2), N1-Ti1-N4 73.5(2), N2-Ti1-N4 77.4(2), N3-Ti1-N4 77.5(1).…”

Section: Resultsmentioning

confidence: 99%

See 3 more Smart Citations

Titanium(IV) Cations with Trigonal Monopyramidal Geometry: Unusual Lewis Acids Supported by a Triaryl Triamidoamine Ligand

Ghana

Krüchten

Spaniol

et al. 2019

Chemistry A European J

View full text Add to dashboard Cite

Protonolysis of the titanium alkyl complex [Ti(CH2SiMe3)(Xy‐N3N)] (Xy‐N3N=[{(3,5‐Me2C6H3)NCH2CH2}3N]3−) supported by a triamidoamine ligand, with [NEt3H][B(3,5‐Cl2C6H3)4] or [PhNMe2H][B(C6F5)4] afforded the cations [Ti(Xy‐N3N)][A] (A−=[B(3,5‐Cl2C6H3)4]− (1[B(ArCl)4]; B(ArCl)4=tetrakis(3,5‐dichlorophenyl)borate); A−=[B(C6F5)4]− (1[B(ArF)4]; B(ArF)4=tetrakis[3,5‐bis(trifluoromethyl)phenyl]borate). These Lewis acidic cations were reacted with coordinating solvents to afford the cations [Ti(L)(Xy‐N3N)][B(C6F5)4] (2‐L; L=Et2O, pyridine and THF). XRD analysis revealed a trigonal monopyramidal (TMP) geometry for the tetracoordinate cations in 1[B(ArX)4] and trigonal bipyramidal (TBP) geometry for the pentacoordinate cations in 2‐L. Variable‐temperature NMR spectroscopy showed a dynamic equilibrium for 2‐Et2O in solution, involving the dissociation of Et2O. Coordination to the titanium(IV) center activated the THF molecule, which, in the presence of NEt3, underwent ring‐opening to give the titanium alkoxide [Ti(O(CH2)4NEt3)(Xy‐N3N)][B(3,5‐Cl2C6H3)4] (3). Hydride abstraction from Cβ,eq of the triamidoamine ligand arm in [Ti(CH2SiMe3)(Xy‐N3N)] or [Ti(NMe2)(Xy‐N3N)] with [Ph3C][B(3,5‐Cl2C6H3)4] led to the diamidoamine–imine complex [Ti(R){(Xy‐N=CHCH2)(Xy‐NCH2CH2)2N}][B(3,5‐Cl2C6H3)4] (R=CH2SiMe3 (4 a); R=NMe2 (4 b)). Hydride addition to 4 b with [Li(THF)][HBPh3] gave [Ti(NMe2)(Xy‐N3N)], whereas KH deprotonated further to give [Ti(NMe2){(Xy‐NCH=CH)(Xy‐NCH2CH2)2N}] (5). XRD on single crystals of 3 and 4 b confirmed the proposed structures.

show abstract

Section: Resultscontrasting

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

See 2 more Smart Citations

Titanium(IV) Cations with Trigonal Monopyramidal Geometry: Unusual Lewis Acids Supported by a Triaryl Triamidoamine Ligand

Ghana

Krüchten

Spaniol

et al. 2019

Chemistry A European J

View full text Add to dashboard Cite

show abstract

“…Preparation of 2,2-diaryl-1,3,2-oxazaborolidin-5-ones was achieved by rst preparation of the triethylammonium tetra-arylborate as previously reported, 25 followed by condensation of the ammonium salt with Lvaline in overnight reuxing toluene in excellent yields. Generally, the desired compounds were puried by precipitation or recrystallization, overcoming the use of chromatography.…”

Section: Resultsmentioning

confidence: 99%

Base catalysed N-functionalisation of boroxazolidones

et al. 2017

View full text Add to dashboard Cite

A method for the condensation of boroxazolidones derived from L-valine with aromatic aldehydes, catalysed by 1,5,7-triazabicyclo[4.4.0]dec-5-ene was developed. The preparation and isolation of a series of highly functionalised stable ketimines derived from the reaction of 2,2-diaryl-1,3,2-oxazaborolidin-5-ones with aryl aldehydes is herein described. Several unreported boroxazolidones were prepared by condensation of triethylammonium tetra-arylborates with L-valine in up to 98% yield. The newly synthesised compounds were determined to be moderately cytotoxic against colorectal adenocarcinoma cells, with the best compound in this series having an IC 50 of 76 mM. A brief inspection of the effect of the same compound against human brain astrocytoma cells showed an IC 50 of 268 mM. IntroductionSynthesis of boron compounds derived from biomolecules such as sugars, amino acids, peptides and nucleic acids has been an extensive and foremost area of research in the last two decades. 1Among other subjects, much interest has been devoted to molecules containing boron-nitrogen bonds. These compounds can possess broad biological activity 2 such as insecticidal, fungicidal, herbicidal and antibacterial properties.3 The ability of several boron compounds, namely those derived from a-amino acids, to interact with tumour cells has opened new venues for their use as part of boron neutron capture therapy.4 The biological properties of chelates containing N-B bonds have also been reported to include apoptotic activity in tumour cells, 5 an ability to disturb calcium channel transporters, 6 inhibition of human neutrophile elastase, 7 and modulation of human phenylalanine hydroxylase activity. Boroxazolidones, a particular kind of N-B bond-containing compounds, generally obtained by reacting a-amino acids with boranes or borinates, were rstly reported in 1962.9 Glycine and L-methionine derivatives were then prepared by the reaction of these amino acids with trialkyl and triaryl boranes in reuxing xylene.9a Since then, several methods for preparation of boroxazolidones with alkyl groups, hydrogens and halogens on boron have been developed. Skoog reported the use of a diaryl alkyl borinate in the condensation with glycine, alanine and leucine 10 and later Neens described the preparation of several a-amino acid derivatives aer reaction with a slight excess of triethylborane or triphenylborane in THF. 11 A different procedure, comprising the reaction of a-amino acids with sodium tetraphenylborate in the presence of hydrochloric acid in water was developed by Baum.12 This procedure was then applied to the preparation of boroxazolidones derived from glycine, alanine, phenylalanine, proline, cysteine and tyrosine in moderate to good yields. The preparation of 2,2-diphenylboroxazolidones is usually achieved by reaction of the a-amino acid with diphenylborinic acid under basic conditions. 5b,13Boroxazolidones have also been employed in organic synthesis. The higher reactivity of the 2,2-dialkyl boroxazolidones towards solvolysis, namely w...

show abstract

Reactivity of an All‐Ferrous Iron–Nitrogen Heterocubane under Reductive and Oxidative Conditions

Lichtenberg

Prokopchuk

Adelhardt

et al. 2015

Chemistry A European J

View full text Add to dashboard Cite

The reactivity of the all-ferrous FeN heterocubane [Fe4 (Ntrop)4 ] (1) with i) Brønsted acids, ii) σ-donors, iii) σ-donors/π-acceptors, and iv) one-electron oxidants has been investigated (trop = 5H-dibenzo[a,d]cyclo-hepten-5-yl). 1 showed self-re-assembling after reactions with i) and proved surprisingly inert in reactions with ii) and iii), with the exception of CO. Reductive and oxidative cluster degradation was observed in reactions with CO and TEMPO, respectively. These reactions yielded new cluster compounds, namely a trinuclear bis(μ3 -imido) 48 electron complex in the former case and a tetranuclear all ferric μ-oxo-μ-imido species in the latter case. Characterization techniques include NMR and in situ IR spectroscopy, single crystal X-ray analysis, Mössbauer spectroscopy, cyclic voltammetry, magnetic susceptibility measurements, and DFT calculations.

show abstract

Preparation of Triethylammonium Tetra-Arylborates (TEATABs): Coupling Partners for the Suzuki Reaction

Cited by 11 publications

References 28 publications

Titanium(IV) Cations with Trigonal Monopyramidal Geometry: Unusual Lewis Acids Supported by a Triaryl Triamidoamine Ligand

Titanium(IV) Cations with Trigonal Monopyramidal Geometry: Unusual Lewis Acids Supported by a Triaryl Triamidoamine Ligand

Base catalysed N-functionalisation of boroxazolidones

Reactivity of an All‐Ferrous Iron–Nitrogen Heterocubane under Reductive and Oxidative Conditions

Contact Info

Product

Resources

About