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ULTRASONIC IRRADIATION IN THE SYNTHESIS OF TRIETHYLBORANE FROM ETHYL BROMIDE VIA ETHYLALUMINIUM SESQUIBROMIDE
Ethyl bromide and aluminum powder were irradiated with ultrasound to form ethylaluminum sesquibromide, which was then treated with triethyl borate to give triethylborane in satisfactory yield and purity.In comparison to other existing methods, ultrasonic irradiation seems to be a simple and effective process for the synthesis of organoboron compounds.
Liou, Kou-Fu,Yang, Paw-Hwa,Lin, Yih-Tsung
p. 145 - 150
(1985)
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Synthesis and structural characterization of the first seven-vertex nido-carborane anion: nido-3,4-Et2C2B5H6-
The reaction of closo-2,3-Et2C2B5H5 with Li-(BEt3)H in the presence of (CH3)4NCl has been found to result in the formation of the first seven-vertex nido-carborane anion nido-3,4-Et2C2B5H6-. A single-crystal X-ray study has demonstrated that the anion adopts an open-cage geometry based on a dodecahedron missing one five-connected vertex. Crystal data: space group P212121, Z = 4, a = 9.257 (1) ?, b = 9.359 (3) ?, c = 17.803 (2) ?. The structure was refined by full-matrix least squares to a final R of 0.055 and Rw of 0.064 for the 1128 unique reflections having Fo2 > 3σ(Fo2).
Beck, Jeffrey S.,Quintana, William,Sneddon, Larry G.
p. 1015 - 1016
(1988)
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REACTION OF DIETHYLHYDROXYBORANE WITH TRIALKYLALUMINIUM
The reaction of diethylhydrodryborane with trialkylaluminium has been studied.Trialkylboranes and diethyltriisobutydialuminium dioxide were isolated and characterized.A two-stage mechanism is proposed for the formation.
Synoradzki, Ludwik,Boleslawski, Marek,Lewinski, Janusz
p. 1 - 4
(1985)
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Lewis acid catalysis: Regioselective hydroboration of alkynes and alkenes promoted by scandium triflate
The first commercially available scandium-catalysed selective hydroboration of alkynes and alkenes with HBpin (pin = OC-Me2CMe2O) in the presence of a catalytic amount of NaHBEt3 has been developed. This protocol can be applicable to a wide range of substrates including aromatic, aliphatic with cyclic and acyclic side chains, and heteroaryl systems with broad functional-group compatibility. Mechanistic studies revealed that the reaction occurs in a syn fashion via the σ-bond metathesis between the alkenyl scandium species and HBpin.
Mandal, Souvik,Verma, Piyush Kumar,Geetharani
supporting information
p. 13690 - 13693
(2019/01/03)

Aluminum Hydride Catalyzed Hydroboration of Alkynes
An aluminum-catalyzed hydroboration of alkynes using either the commercially available aluminum hydride DIBAL-H or bench-stable Et3Al?DABCO as the catalyst and H-Bpin as both the boron reagent and stoichiometric hydride source has been developed. Mechanistic studies revealed a unique mode of reactivity in which the reaction is proposed to proceed through hydroalumination and σ-bond metathesis between the resultant alkenyl aluminum species and HBpin, which acts to drive turnover of the catalytic cycle.
Bismuto, Alessandro,Thomas, Stephen P.,Cowley, Michael J.
supporting information
p. 15356 - 15359
(2016/12/06)

Scope and post-transformations for the borane-isocyanide multicomponent reactions: Concise access to structurally diverse heterocyclic compounds
A recently described family of multicomponent reactions (MCRs) involving isocyanides, aldehydes, dipolarophiles and alkylboranes that yield highly substituted aziridines, oxazolidines and pyrrolidines has been studied in detail. In this work the scope of these processes is significantly increased by preparing the borane input through hydroboration of alkenes or organometallic processes, in tandem with the MCR. The aldehyde range is also expanded, and indole-3-carbaldehydes yield reactive imines and bis-indolyloxazolidines, depending on the electron density of the heterocycle. Finally, the obtained adducts constitute an ideal platform to generate structurally diverse compounds using simple post-condensation modifications. In this way, indole imines undergo stereoselective hydrocyanation and oxazolidines are reductively opened to give amino alcohols. Additionally, palladium-, ruthenium- and gold-catalyzed processes lead to a variety of complex heterocycles. The methodology is simple, efficient and highly divergent, leading to an array of interesting scaffolds for medicinal chemistry. Copyright
Kielland, Nicola,Vicente-Garcia, Esther,Reves, Marc,Isambert, Nicolas,Arevalo, Maria Jose,Lavilla, Rodolfo
p. 3273 - 3284
(2013/12/04)

Generation of organolithium compounds bearing super silyl ester and their application to Matteson rearrangement
It's super-silyl-fragilithyl-ester-aryl-docious: The super silyl group is a strong protecting group for carboxylic acids and provides a method for direct lithiation that is compatible with the ester moiety. Organolithium compounds bearing a super silyl ester react with a variety of electrophiles in high yields (see scheme). The reaction of lithiated super silyl chloroacetate with a boron compound gives α-functionalization of the ester moiety by Matteson rearrangement. Copyright
Oda, Susumu,Yamamoto, Hisashi
supporting information
p. 8165 - 8168
(2013/08/23)

Electron-rich N-heterocyclic silylene (NHSi)-iron complexes: Synthesis, structures, and catalytic ability of an isolable hydridosilylene-iron complex
The first electron-rich N-heterocyclic silylene (NHSi)-iron(0) complexes are reported. The synthesis of the starting complex is accomplished by reaction of the electron-rich Fe0 precursor [(dmpe)2Fe(PMe 3)] 1 (dmpe =1,2-bis(dimethylphosphino)ethane) with the N-heterocyclic chlorosilylene LSiCl (L = PhC(NtBu)2) 2 to give, via Me3P elimination, the corresponding iron complex [(dmpe)2Fe(←:Si(Cl)L)] 3. Reaction of in situ generated 3 with MeLi afforded [(dmpe)2Fe(←:Si(Me)L)] 4 under salt metathesis reaction, while its reaction with Li[BHEt3] yielded [(dmpe) 2Fe(←:Si(H)L)] 5, a rare example of an isolable SiII hydride complex and the first such example for iron. All complexes were fully characterized by spectroscopic means and by single-crystal X-ray diffraction analyses. DFT calculations further characterizing the bonding situation between the SiII and Fe0 centers were also carried out, whereby multiple bonding character is detected in all cases (Wiberg Bond Index >1). For the first time, the catalytic activity of a SiII hydride complex was investigated. Complex 5 was used as a precatalyst for the hydrosilylation of a variety of ketones in the presence of (EtO)3SiH as a hydridosilane source. In most cases excellent conversions to the corresponding alcohols were obtained after workup. The reaction pathway presumably involves a ketone-assisted 1,2-hydride transfer from the SiII to Fe0 center, as a key elementary step, resulting in a betaine-like silyliumylidene intermediate. The appearance of the latter intermediate is supported by DFT calculations, and a mechanistic proposal for the catalytic process is presented.
Blom, Burgert,Enthaler, Stephan,Inoue, Shigeyoshi,Irran, Elisabeth,Driess, Matthias
p. 6703 - 6713
(2013/06/26)

METHOD FOR PRODUCING TRIHYDROCARBYLBORANE
The present invention provides a method for industrial production of trihydrocarbylborane which method is excellent both in quality and in cost. The present invention is concerned with production of trihydrocarbylborane, comprising a reaction synthesizing the trihydrocarbylborane and aluminum oxide from trihydrocarbylboroxine and trihydrocarbylaluminum, characterized in that the reaction is allowed to proceed so that the trihydrocarbylaluminum is present at the end of the reaction in an amount of 0.5 moles or more per mole of the aluminum oxide produced in the reaction.
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(2008/06/13)

METHOD FOR PRODUCING HEXAALKYLBORAZINE
The invention relates to a method for producing hexaalkylborazine represented by formula 2 from a borazine represented by the formula 1, an alkene and a ligand transition-metal complex catalyst. For both formulas 1 and 2, R1 represents an alkyl group and may be the same or different. R2 represents a hydrogen atom or an alkyl group, and may be the same or different, and at least one of the R2 is a hydrogen atom, and R3 represents a an alkyl group, and may be the same or different.
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(2008/06/13)

Synthesis, structures, and ring-opening polymerization reactions of substituted cyclopentadienyl complexes of zinc
The reaction of 2 equiv of the new pyrrole-substituted cyclopentadienyl ligand cyclo-C4H4-NSiMe2C5 H5 (2a, CppyH) with Zn[N(SiMe3)2]2 gives the bis(cyclopentadienyl)zinc complex Zn(Cppy)2 (3a). The reaction of 2a and the related derivatives cyclo-2,5-Me2C4 H2NSiMe2C5H5 (2b, CppymeH) and 3,5-Me2C6H3 CH2CMe2C5H5 (2c, CpmesH) with dibutylmagnesium gives the corresponding magnesocenes MgCpR2 (3a-c). Prolonged heating of the appropriate cyclopentadiene with zinc dialkyls in toluene, or alternatively stirring with [XZnN(SiMe3)2]2 in toluene at 40°C for 1 h, gives the monocyclopentadienyl zinc alkyl complexes CpRZnX (6a, CpR = Cppy, X = Me; 6c, CpR = Cpmes, X = Me; 7a, CpR = Cppy, X = Et; 7c, CpR = Cpmes, X = Et), which provide spectroscopic evidence for a Zn...(hetero)arene interaction. Addition of tetramethylethylenediamine (TMEDA) gives CpRZnX(TMEDA) (8a, b, X = Me; 9a-c, X = Et). The crystal structures of 8b and 9c show η2-bound cyclopentadienyl ligands, with one long and one short Zn-C interaction. The reaction of 7c with B(C6F5)3 in toluene proceeds with alkyl/C6F5 exchange to give Cpmes Zn(C6F5) (10). Treatment of 9c with B(C6F5)3 in toluene results in an ionic product, [CpmesZn(TMEDA)]+[EtB(C6 F5)3]- (11). On the other hand, the reaction of 9a with B(C6F5)3 in toluene or dichloromethane proceeds with β-H abstraction, with concomitant loss of ethene, as well as both ethyl and cyclopentadienyl abstraction. Both 11 and 9a/B(C6 F5)3 mixtures catalyze the polymerization of cyclohexene oxide and ε-caprolactone.
Walker, Dennis A.,Woodman, Timothy J.,Schormann, Mark,Hughes, David L.,Bochmann, Manfred
p. 797 - 803
(2008/10/08)

Process for the synthesis of 1,3-diols
An improved process for the preparation of cis-1,3-diols is described where a beta hydroxy ketone is treated with a trialkylborane or dialkylalkoxyborane or a mixture of a trialkylborane and a dialkylalkoxyborane followed by recovery and reuse of the alkylborane species to convert additional beta hydroxy ketone to the cis-1,3-diol.
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(2008/06/13)

Reactions of zinc dialkyls with (perfluorophenyl)boron compounds: Alkylzinc cation formation vs C6F5 transfer
Reaction between ZnR2 and [H(OEt2)2] [B(C6F5)4] in ether leads to the salts [RZn(OEt2)3]-[B(C6F5)4], while mixtures of ZnR2 (R = Me, Et) and B(C6F5)3 in toluene-d8 undergo facile alkyl/C6F5 group exchange to give Zn(C6F5)2·(toluene). Mixtures of ZnR2 and B(C6F5)3 in hydrocarbon/diethyl ether solvent mixtures react with alkyl transfer to afford the ion pairs [RZn(OEt2)3][RB(C6 F5)3], whereas the reaction of ZnEt2 with [Ph3C][B(C6F5)4] in toluene-d8 proceeds with β-H abstraction to give ethene and Ph3CH, with the subsequent rapid formation of Zn(C6F5)2.
Walker, Dennis A.,Woodman, Timothy J.,Hughes, David L.,Bochmann, Manfred
p. 3772 - 3776
(2008/10/08)

Novel organoborane Lewis acids via selective boron-tin exchange processes - Steric constraints to electrophilic initiation by the boron halide
With the purpose of preparing novel mono- and bidentate organoboron Lewis acids, the scope and limitations of synthesizing the requisite organoboranes by the boron-tin exchange between a boron halide and the appropriate organostannane have been examined in detail. The following organotin derivatives have been obtained either from the corresponding RMgBr or RLi reagent and MenSnCl4-n or from a Barbier procedure using the organic halide, Me3SnCl and magnesium metal: 1,2-bis(trimethylstannyl)ethyne, o-, m-, and p-bis(trimethylstannyl)benzenes, α,o-bis(trimethylstannyl)toluene, α,α-bis(trimethylstannyl)-o-xylene, and 2,2-dimethyl-2-stannaindane. The individual interaction of the 1,2-bis(trimethylstannyl)ethyne and the isomeric bis(trimethylstannyl)benzenes with Et2BBr produced the corresponding bis(diethylboryl)-derivatives. By contrast, with Et2BCl the α,o-bis(trimethylstannyl)toluene gave only o-diethylboryl-α-trimethylstannyltoluene and with BCl3 the α,α′-bis(trimethylstannyl)-o-xylene formed only α,α′-bis-(chlorodimethylstannyl)-o-xylene. Furthermore, in the attempted double boron-tin exchange between o-bis(trimethylstannyl)benzene and BCl3, an unprecedented rearrangement of the 1-(dichloroboryl)-2-(trimethylstannyl)benzene intermediate into its 1-[chloro(methyl)boryl]-2-(chlorodimethylstannyl) isomer was observed. Likewise, o-bis(trimethylstannyl)benzene with PhBCl2 produced by a similar rearrangement 1-[methyl(phenyl)boryl]-2-(chloro-dimethylstannyl)benzene. The thermolysis of such boranes led variously to definite dimers or ill-defined oligomers. Preliminary studies of the properties of these organoboranes have identified the heightened Lewis acidity of 1,2-bis(diethylboryl)ethyne and the π-electron delocalization involving the 2pΖ-boron orbitals in the 9,10-dihydro-9,10-diboraanthracene system. Finally, an electronic mechanism for the boron-tin exchange has been developed to account for the selectivity of the boron halide's attack at unsaturated carbon-tin bonds.
Eisch, John J.,Kotowicz, Boguslaw W.
p. 761 - 769
(2007/10/03)

A Tricyclic Tetraboradisiladodecane from Dimethyl-di-1-propynylsilane and Ethyldiboranes(6)
The exhaustive hydroboration of the (CC)-groups in Me2Si(CCMe)2 (A) by adding ethyldiboranes(6) at room temperature is presumed to lead initially to the formation of a mixture of the threo- and erythro-3,3,5,6-tetrakis(diethylboryl)-4,4-dimethyl-4-silaheptanes (1a,b).The threo-1a reacts further by =BH borane catalysed intermolecular condensation to the substituted disilatetraboratricyclo6,9>dodecane 2 with formula , whose crystal structure a = 19.696(2), b = 10.371(1), c = 16.580(2) Angstroem; β = 125.90(1) deg; at 122 K> has been established by X-ray diffraction.In contrast, the erythro-1b undergoes intramolecular, thermal elimination of Et3B to give the 1,2-diethyl-2,4-bis(diethylboryl)-3,3,5-trimethyl-3-silaborolane (4).If A is added to an excess of undiluted B ( hydride-bath ), then the two substituted diastereomers of the 1-carba-arachno-pentaboranes(10) (endo/exo-Et,SiHMe2) (3a,b), are formed preferentially as the result of an initial SiC-cleaved hydroboration. - Keywords: Hydroboration of Si-CC Grouping, Regioselectivity, Diborylpropylsilanes, Stereoisomers
Koester, Roland,Seidel, Guenter,Boese, Roland,Wrackmeyer, Bernd
p. 439 - 447
(2007/10/02)

Beitraege zur Chemie des bors, 226: Funktionalisierung von Alkinylboranen-Umsetzung mit Nucleophilen
The synthesis of alkynylboranes RR'B-CC-R" 1-3 and their reactions with various nucleophiles are described (R, R' = Me2N, Cl, alkyl; R" = Me, Ph).Although these compounds can be looked upon as inorganic Michael systems, nucleophiles such as alcohols, amines, amides and various carbon nucleophiles attack exclusively at the boron atom (analogous to a 1,2- attack).Thus, a nonvenient means of functionalization of alkynylboranes at the boron atom with preservation of the B-CC moiety is described, and alkynylboranes with R,R' = Me2N, N(H)iPr, pyr, OiPr, Me, Mes, CC-SiMe3 were obtained in good yield and characterized by spectroscopic methods.The pathway for the reaction of (Me2N)2B-CC-Ph with carbon nucleophiles to tris(alkyl)boranes has been elucidated.The implications both for the electronic properties and the chemical reactivity of alkynylboranes are discussed.Keywords: Alkynylboranes, Nucleophilic attack, Organoboron compounds, Inorganic Michael systems; Boron; Alkyne
Feulner, Herta,Metzler, Nils,Noeth, Heinrich
p. 51 - 62
(2007/10/02)

Rearragement and Degradation of Bicyclic Amine-Tetraalkyldiboroxanes
The amine-tetraalkyldiboroxanes 1,4,7,7' = Et; 1b: R1,4,7 = Et, R7' = Ph; 1b': R4,7,7' = Et, R1 = Ph; 1c: R1,7,7' = Et, R4 = Ph> react on heating by EtBO elimination and allylborane rearrangement to yield the allyl-aminoboranes Me2NB(Et)CH2C(R4)=C(R7,7') 4,7,7' = Et, 2b/2b': R4 = Et, R7,7' = Et, Ph; 2c: R4 = Ph, R7,7' = Et>: On heating above 60 deg C the diastereomeric syn/anti-1d/1d' (1d: R1,7 =C8H14, R4,7' = Et; 1d': R1,7' = C8H14, R4,7 = Et) give the unsaturated rac-amino-trialkyldiboroxane (rac-3) (X-ray structure analysis) by intramolecular 1,2-deaminoboration. rac-3 is characterized by reaction with (Et2BH)2 and (Et2BD)2 with formation of the 1,2,6-oxadiborinane 5 by evolution of H2 or HD respectively.The intramolecular CH-borylation of rac-3 is compared with those of the thujopsen hydrocarbons I-III. - Key Words: Amine-Diboroxanes, bicyclic / 1,2-Deaminoboration, intramolecular / Deoxy boration / Allyl-aminoboranes, organosubstituted, rearrangement / C-Borylation
Koester, Roland,Schuessler, Wilhelm,Seidel, Guenter,Blaeser, Dieter,Boese, Roland
p. 1843 - 1850
(2007/10/02)

Organoboryl Sulfates - Preparation and Characterisation
Triethylborane (3) reacts with sulfuric acid to form the sulfate Et2BOS(O2)OBEt2 (1a), which can also be prepared from (Et2B)2O (4a) and SO3.Sulfate 1a reacts with (C8H14B)2O (4b) to give the solid sulfate C8H14BOS(O2)OBC8H14 (1b) and 4a.Compound 1b is also obtained by treating 4b with SO3.The reaction of 4a with sulfuric acid leads to the crystalline cyclic sulfate (2a) (X-ray structure analysis). 2a is also available from triethylboroxin (5) on reaction with SO3.The diboroxanes 4a and 4b and H2SO4 form insoluble 1:1 addition complexes 4a*H2SO4 and 4b*H2SO4, which react on heating at about 60 deg C to yield the cyclic sulfates 2a and (2b), respectively. - Key Words: Boryl sulfates, diethyl-, 9-BBN- / Sulfatoboranes / Ethylboronic acid, sulfuric acid, mixed anhydrides of / Sulfatization of boranes / Diboroxane, cyclic
Koester, Roland,Schuessler, Wilhelm,Blaeser, Dieter,Boese, Roland
p. 1593 - 1598
(2007/10/02)

Substituted 1,2-Diborylalkenes - Preparation and Photoisomerization
The organo(halo)substituted cis-1,2-diborylalkenes cis-R2BC(R)=C(Et)BEt2 (Z)-1 to (Z)-14 are prepared CR> and ClBR2; route II from cis-R3SnC(R)=C(Et)BEt2 and RnBHal3+n, n = 0-2; (Z)-11 (route III): cis-ClB(Ph)CH=C(Et)BEt2 and Me3SiOMe>.Their 11B- and 13C-NMR data show the degree of pz(B)/(C=C) ? overlap and are compared with the corresponding data of the monoboryl alkenes ; the cis-2-boryl-1-silylalkenes , and the cis-2-boryl-1-stannyl-alkenes . - Compounds (Z)-3, (Z)-4, (Z)-9, (E)-18, and (E)-19 with one or two nearly coplanar pz(B) and pz(C=C) groups (pl-R2B) are isomerized by UV irradiation to their equilibria with the corresponding trans isomers (E)-3, (E)-4, (E)-9, (Z)-19, resp., with one or two nearly orthogonal pz(B) and pz(C=C) groups (or-R2B).Irradiation of (Z)-9 gives the isomer pair (Z/E)-iso-9 by a Ph/Et exchange between the two boron atoms.Key Words: cis-1,2-Diborylalkenes, organo-, halosubstituted / cis/trans 1,2-Diborylakenes, organosubstituted, photoisomerization of / cis/trans-2-Boryl-1-silylalkenes, organosubstituted, photoisomerization of / Diorganoboryl groups of alkenes, or- and pl-B(pz)orbitals / Monoborylalkenes, organosubstituted
Koester, Roland,Seidel, Guenter,Wrackmeyer, Bernd
p. 319 - 330
(2007/10/02)

Organosubstituted cis-1,2-Diborylalkenes as Electrophilic Chelates
Triethylborane (1), 9-ethyl-9-borabicyclononane (9-ethyl-9-BBN) (2), and the cis-1,2-diborylalkenes (Z)-R2BC(R')=C(Et)BEt2 react with alkali metal salts MX in toluene to give the borates MX-1, MX-2, and the cyclic cis-1,2-diborates , resp., with BHB- and B(OR)B-bridges (IR, Multi NMR).Reaction of 1, 2, and 3 - 6 with KCN leads to the monoborates KCN-1, KCN-2, and to the acyclic cis-1,2-diborates KCN-3 to KCN-7. - The cis-2-Boryl-1-silylalkenes (E)-Me3SiC(R')=C(Et)BEt2 and KX form the acyclic borates K.The cyclic salts KOtBu-4 and KOSiEt3-4 undergo a B-substituent exchange to the acyclic cis-1,2-diborates K (K-10: R = tBu; K-11: R = OSiEt3).Key Words: cis-1,2-Diborylalkenes, electron acceptors, anion sponge / Diborates, hexaorgano, μ-hydro, μ-alkoxy, alkali metal salts / Borates, hydrotriorgano- / Substituent exchange, diborates
Koester, Roland,Seidel, Guenter,Wagner, Klaus,Wrackmeyer, Bernd
p. 305 - 318
(2007/10/02)

Alkalimetal Trialkylhydroxyborates and (Alkalimetaloxy)dialkylboranes
Et3B (1) and 9-Et-9-BBN (2) react with alkalimetal hydroxides (LiOH, NaOH, KOH) to yield the alkalimetal hydroxytriorganoborates M-3 and M-4, resp.Heating (about 100 deg C) of the borates, catalyzed by NaHBEt3, leads to elimination of ethane with formation of the boranes MOBEt2 (M-5, M = Na, K) or MOBC8H14 (M-7, M = Li, Na, K), which associate to compounds with BOB, BOM, or MOM bridge bonds.At temperatures higher than 160 deg C (without catalyst), M-3 (M = Li, Na) and Li-4 dissociate.Na-4 is dehydroborated with formation of H2 and NaOB(Et)C8H13 (Na-9).From K-7 and ClSiMe3 9-Me3SiO-9-BBN (10) is obtained.Na-9 reacts with ClSiMe3 to give a mixture of the unsaturated mixed borane 11 and the mixed diboroxane 12.The degree of the association of the alkalimetal compounds were determined by the specific electric conductivity measurements (κ) and by 17O-NMR spectroscopy.Key Words: Borates, trialkyl-, hydroxy- / Alkalimetal hydroxides / BC protolysis, BH-borate catalysis / Boranes, (alkalimethaloxy)dialkyl- / Dimers with BOB bonds, MOM bonds / 1,3,2-Diboroxanes, organosubstituted
Koester, Roland,Seidel, Guenter,Wrackmeyer, Bernd
p. 617 - 626
(2007/10/02)

Organosubstituted 2,5-Dihydro-1,2,5-azasilaboroles - Methods of Preparation and Spectroscopic Characterisation
The compounds (E)-R22R2'ElIVC(R3)=C(R4)BR25 are prepared from Na34,5BCCR3> with ClElIVR22R2' IV = Si, Ge, Sn> or from R22R2'SiCCR3 with BR34,5 (R4,5 = CH3, C6H5).The substituted silol 1z is obtained from (CH3)2Si(CCCH3)2 and B(C2H5)3, the mixture of (Z/E)-1t from (CH3)3SiCCH and B(C2H5)3. - ClSi(CH3)2C(CH3)=C(C2H5)B(C2H5)Cl (C) reacts with LiN(CH3)2 to form (CH3)2NSi(CH3)2C(CH3)=C(C2H5)B(C2H5)N(CH3)2 (E)-1n. - (E)-1a to (E)-1g or (E)-1aGe and (E)-1aSn add MNH2 (M = Na, K) to yield the compounds MNH2-1, which react to the solid alkaline metal heterocycles M-2 after liberating R2H.From (E)-1a or (E)-1b with LiNH2 the compounds (E)-C2H5CH=CR4Si(CH3)3 (A, B) are obtained. - On heating M-2a to M-2g eliminate R5H (C2H6) and smoothly from the solid compounds M-3, from which the heterocycles (4a-f) are prepared with CH3I.The 1-phenyl derivatives 5a,b are obtained from 4a,b with aniline.M-2c,d react with HCl to give the compounds 6c,d from which 7c,d are formed after C2H6 elimination.The 5-chloro compound 4i is used for the preparation of the heterocycles 4 with R5 = H, C(CH3)3, and N(CH3)2. - All compounds 1-7 are characterized by multinuclear NMR spectroscopy, the volatile compounds 1 and 4-7 also by their mass spectra. - Key Words: Organoboranes, unsaturated / Organosilanes, unsaturated / Aminotriorganoborates / Cyclization / 2,5-Dihydro-organo-1,2,5-azasilaboroles
Koester, Roland,Seidel, Guenter,Wrackmeyer, Bernd
p. 1825 - 1850
(2007/10/02)

Substituted 2,5-Dihydro-1,2,5-oxasilaboroles - Preparation, Complexations, and Ring-Opening
The two 4,5-diethyl-2,5-dihydro-2,2-dimethyl-3-organo-1,2,5-oxasilaboroles are prepared from and water via the addition compounds in yields of about 90percent. 2a,b are also obtained directly from 1a,b with acetylacetone or with dry acetic acid. 1b can be prepared from sodium triethylhydroborate (A) via sodium triethyl(3-methyl-3-buten-1-ynyl)borate (B), (Z)-4-(diethylboryl)-2-methyl-3-(trimethylsilyl)-1,3-hexadiene (C), sodium aminodiethylborate (D), 4,5,5-triethyl-2,5-dihydro-3-isopropenyl-2,2-dimethyl-1-sodio-1,2,5-azoniasilaboratole (E), and 4,5-diethyl-2,5-dihydro-3-isopropenyl-2,2-dimethyl-1-sodio-1,2,5-azasilaborole (F).The behaviour of 2a,b towards trimethylphsophane (TMP), γ-picoline (formation of γ-Pic-2a), γ-picoline N-oxide (PNO-2a), trimethylamine N-oxide (2'a, 4, 4'a), methylenetriphenylphosphorane (MTPP-2a), aluminium trichloride (2a-AlCl3), triethylaluminium , trichloroborane (3a), dichloroethylborane (3b), phosphorus pentachloride (3a, 3b), methanol (6a), acetylacetone (5a), propanol (7a, 7c) and towards glacial acetic acid (7a, 9) is described. 5-Chloro-4-ethyl-2,5-dihydro-1,2,2,3-tetramethyl-1,2,5-azasilaborole (1c) is readily obainable from 1a and dichloroethylborane. η4-Complexations of 2b give 10b from (CH3CN)3Cr(CO)3, 11b and 11'b from Fe2(CO)9, 12b from Ru3(CO)12, 13b from C5H5Co(C2H4)2, and 14b from C5H5Rh(C2H4)2 (MS and NMR data).The O-exchange in several reactions was monitored by 17O NMR using 17O-enriched compounds (e.g. 2a*, triethylboroxin*, tetraethyldiboroxane*, water*, methanol*).
Koester, Roland,Seidel, Guenter,Boese, Roland,Wrackmeyer, Bernd
p. 597 - 616
(2007/10/02)

Gas-Phase Lewis Acid-Base Interactions. An Experimental Determination of Cyanide Binding Energies from Ion Cyclotron Resonance and High-Pressure Mass Spectrometric Equilibrium Measurements
Both ion cyclotron resonance and high-pressure mass spectrometric equilibrium techniques have been used to investigate the binding energies of anions to a variety of Lewis acids.From an analysis of the enthalpy changes associated with CN- binding it is evident that in cases of relatively weak binding considerable freedom of rotational motion of CN- in the complex may be retained.Ab initio calculations and experiment suggest that binding through both the N and C sites of CN- is nearly equally favorable in some cases.In contrast to results previously obtained for Bronsted acids which showed that CN- and Cl- bind nearly identically, the present data for Lewis acids show many cases where cyanide is much more favorably bound than chloride, a consequence of enhanced covalent binding of the CN- complexes.New Kroeger Drago parameters derived for CN- support the importance of covalent binding in cyanide adducts.Correlations of binding energy of anions to Lewis acids with the anion proton affinity show excellent linear relationships which may be used to predict binding energetics for new anions.
Larson, J. W.,Szulejko, J. E.,McMahon, T. B.
p. 7604 - 7609
(2007/10/02)

Hydrodesulfurization model complexes: Nucleophilic addition to π-coordinated benzo[b]thiophenes and thiophene
The π-bound thiophene (T) and benzo[b]thiophene (BT) complexes [CpRu(BT)]+, [Cp*Ir(BT)]2+, and [Cp*Ir(T)]2+, models for the adsorption of thiophenic compounds to hydrodesulfurization (HDS) catalyst surfaces, react with a variety of nucleophiles (H-, MeO-, (MeO2C)2CH-, EtS-, and phosphines). The BT complexes yield the first isolable transition-metal cyclohexadienyl complexes derived from fused ring aromatic ligands; four isomers of each cyclohexadienyl complex are produced. The isomers result from addition at the four carbons on the benzene ring; for the nucleophiles studied, addition occurs preferentially at the carbon closest to the sulfur atom, C7. This isomer of CpRu(BT·H) has been characterized by an X-ray structure determination. The T complex reacts with phosphines to produce [Cp*Ir(η4-T·PR3)]2+. Double nucleophilic addition reactions (H- and MeO-) of [Cp*Ir(BT)]2+ and [Cp*Ir(3-MeBT)]2+ are also discussed. Reaction of either NaBEt3H or Cp2Co with [Cp*Ir(T)]2+ results in a 2e reduction of the Ir complex. On the basis of 1H NMR data and by analogy to related complexes, this product is formulated as Cp*Ir(η4-T).
Huckett, Sara C.,Angelici, Robert J.
p. 1491 - 1500
(2008/10/08)

Aminoborane polymers as precursors of C-N-B ceramic materials
Aminoborane polymers were prepared via condensation reactions between polyfunctional amines and either triethylborane or tris(dimethylamino)borane. The products were characterized by chemical and spectroscopic analyses. The thermal degradation of these ma
Maya
p. 1104 - 1107
(2008/10/08)

Reactions of Diphenylphosphane Oxide with Organodiboranes(6) - Structure of a Zwitterionic Compound
(C6H5)2POB(C2H5)2 (3'a), prepared from diphenylphosphane oxide (C6H5)2P(O)H (1) and activated triethylborane (2a*), reacts with tetraalkyldiboranes(6) (R2BH)2 to form the BH3-addition compounds (C6H5)2P(BH3)OBR2 , 2BR , and 3B .The reaction of bis(9-borabicyclononane) (4c)2 with 1 leads to (C6H5)2POBC8H14 (3'c) or 3'c-4a and (C6H5)2PH (7) or (C6H5)2PH-HBC8H14 (7-4c).The crystalline zwitterionic (C6H5)2P(H)OB3 (X-ray analysis) is isolated from the reaction of 1 with (4a)2.
Koester, Roland,Tsay, Yi-Hung,Synoradzki, Ludwik
p. 1117 - 1124
(2007/10/02)

Sodium hydridotrimethylboronate and its ether solvate. Study of hydridotrialkylboronates as reagents for the preparation of beryllium hydrides
Sodium hydridotrimethylborate is tetrameric in benzene solution and its etherate, (NaBMe3H)4OEt2 probably also retains its solid state cubane arrangement in benzene solution.Reactions of NaBR3H (R = Me, Et) in a variety of ratios with halo and organoberyllium compounds have been studied.Exchange between Et2Be and NaBEt3H does not occur to any appreciable extent beyond the EtBH stage and reaction of equimolar EtBeCl and NaBEt3H resulted in the formation of EtBeH, isolated as its trimethylamine complex.NaBR3H and BeCl2 in 1/1, 2/1 and 4/1 ratios did not yield pure beryllium hydrides.
Bell, Norman A.,Coates, Geoffrey E.,Heslop, J. Alan
p. 287 - 292
(2007/10/02)

Reactions of (Organo)phosphorus-Oxygen Compounds with Diorgano-hydro-boranes
Trialkyl phosphites P(OR)3 react with tetraalkyldiboranes(6) (R'2-BH)2 in a temperature-dependent manner between 20 and 130 deg C to form the trialkyl phosphite-boranes (RO)3P-BHR'2, (RO)3P-BH2R', and (RO)3P-BH3, which have various stabilities toward alcohols.With bis(9-borabicyclononane) (1c)2 the easily protolyzed addition compounds are obtained . - Diorgano phosphites (RO)2P(O)H , triorgano phosphates (RO)3PO , and the monosaccharide-diphenyl phosphates 4f, 4g, and 4h are reduced by (1a)2 or (1c)2 to give H2, PH3, and insoluble yellow phosphorus compounds, respectively.Phosphoric acid (4e), their derivatives OP(OBR2)3 , and phenylphosphonic acid C6H5P(O)(OH)2 (6) are not deoxygenated at 130 deg C by (1a)2 to (1c)2. - Diorganophosphoiic acids R2P(O)OH and phenylphosphinic acid C6H5(H)P(O)OH (5c) are reduced by (1a)2-(1c)2.Reaction of 5a with (1a)2 leads to the compounds B(C2H5)2 (8a-BH3), 2BC2H5 , and 3B . 5a reacts with (1c)2 under simultaneous formation of (C6H5)2PH (7) or (C6H5)PH-HBC8H14 (7-1c) and (C6H5)2POBC8H14 (8c) or (C6H5)2P(OBC8H14)-HBC8H14 (8c-1c). - 6 reacts with tetraethyldiboroxane (11a) to form a mixture of the oligomeric compounds - n - (6'a)n.
Koester, Roland,Schuessler, Wilhelm,Synoradzki, Ludwik
p. 1105 - 1116
(2007/10/02)

ULTRASONIC IRRADIATION IN ONE-POT SYNTHESIS OF TRIETHYLALUMINUM ETHERATE AND ITS CONVERSION INTO OTHER ORGANOMETALLIC COMPOUNDS
A mixture of ethyl bromide, aluminum and magnesium powders was irradiated with ultrasound and ethylaluminum sesquibromide(I) formed at room temperature.As soon as diethyl ether was introduced into the reaction medium, ethylmagnesium bromide(II) was formed in situ and subsequently treated with I to give the etherate of triethylaluminum (III, TEA * OEt2) in satisfactory yield (82percent) and purity (98percent).III, thus obtained, could react with triethyl borate or zinc chloride to give triethylborane (90percent) and diethylzinc (82percent) respectively.
Lin, Yih-tsung
p. 277 - 284
(2007/10/02)

An unusual solvent effect in the reaction of ethylmagnesium bromide with triethylborane in ethyl ether or tetrahydrofuran. A simple direct route to tetraorganylborate complexes
The reaction of organic halides, magnesium turnings, and boron trifluoride etherate yields triorganylboranes quantitatively in anhydrous ethyl ether (modified organometallic method) but leads to quantitative formation of tetraorganylborate complexes in tetrahydrofuran. A detailed study of the reaction of ethylmagnesium bromide with triethylborane revealed that essentially no reaction occurs in ethyl ether, EtMgBr + BEt3, but complete combination occurs in tetrahydrofuran, Et4BMgBr. This development provides a simple, convenient route for the synthesis of tetraorganylborate complexes.
Brown, Herbert C.,Racheria, Uday S.
p. 391 - 393
(2008/10/08)

Dimeric (Dihalogenoaluminiooxy)diorganoboranes
Tetraorganodiboroxanes R2BOBR2 (1) 2 = 1,5-cyclooctanediyl = C8H14> and aluminium trihalides AlHal3 (2) n: Hal = Cl, (2b)2: Hal = Br> eliminate halogenodiorganoboranes R2BHal (4) in yields >90percent to give crystalline, in solution and in the solid state dimeric (dihalogenoaluminiooxy)diorganoboranes (Hal2AlOBR2)2 (3xy)2 2: R = C2H5, Hal = Cl; (3ba)2: R2 = C8H14, Hal = Cl; (3ab)2: R = C2H5, Hal = Br; (3bb)2: R2 = C8H14, Hal = Br>, having two AlOAl bonds . - The X-ray analyses of (3aa)2 and (3bb)2 confirmed the four-membered AlOAlO ring with the exocyclic O-diorganoboryl groups.
Koester, Roland,Tsay, Yi-Hung,Krueger, Carl,Serwatowski, Janusz
p. 1174 - 1188
(2007/10/02)

Novel Organoboron-Oxygen-Halogenaluminium Compounds from Triorganoboroxins with Aluminium Trihalides
4 mol of triorganoboroxins (RBO)3 (1) react with 6 mol of aluminium trihalides AlHal3 (2) under cleavage of 4 mol dihalogenoorganoboranes RBHal2 (3) leading in high yields to 2 mol of compounds 4 having the composition R4Al3B4Hal5O6 (MS analyses) .The structure of 4aa, 4ba, 4ca, and 4bb in solution is deduced from spectroscopic data (IR; 1H, 11B, 17O and 27Al NMR).The molecular structure of the solid (C6H5)4Al3B4Cl5O6 (4da) with two (AlOBOBO)-rings bonded through one penta-coordinated aluminium atom was determined by X-ray diffraction analysis.
Koester, Roland,Angermund, Klaus,Serwatowski, Janusz,Sporzynski, Andrzej
p. 1301 - 1314
(2007/10/02)

Contributions to the Chemistry of Boron, 152. 1,3,2,4-Diazaphosphaboretidines and 1,3,2,4-Diazasilaboretidines Prepared via Intra- and Intermolecular Cyclocondensation
1,3,2,4-Diazaphospha(sila)boretidines 5 and 9 are accessible via thermal decomposition of compounds of type E(NR'-BR2)2 (8) or from organoboron dihalides or boron trihalides and E(NR'Li)2 .The formation of 1,3-di-tert-butyl-4-methyl(or ethyl)-1,3,2,4-diazaphospha(sila)boretidines from the precursor E(NR'-BR2)2 proceeds by an intramolecular cyclocondensation.NMR data reveal less shielded B and P atoms in the new heterocycles as compared with noncyclic compounds; this is attributed to a strained ring system.A tetracoordinated as well as a tricoordinated boron atom is observed in CH3(O)P(NR'BR2)2 compounds resulting from intramolecular BO coordination.
Jacksties, Wolfgang,Noeth, Heinrich,Storch, Wolfgang
p. 2030 - 2043
(2007/10/02)

Preparation of O-Diorganoboryl Derivatives of Several (Organo)-Phosphorus Acids
The O-diorganoboryl derivatives 4-9 of (organo)-phosphorus acids are prepared from diphenylphosphinic acid (1a), dicyclohexylphosphinic acid (1b), phenylphosphinic acid (1c), phenylphosphonic acid (2), and phosphoric acid (3) using activated triethylborane (method A), bis-9-borabicyclononane (method B), or tetraethyldiboroxane (method C).By O-diorganoborylation, 1a-c give the compounds RR'P(O)OB(C2H5)2 , RR'P(O)OBC8H14 , 2 reacts to form C6H5P(O)(OBR2)2 , and 3 yields the compounds OP(OBR2)3 . - The IR and MS data for 4-9, which associate in solution, are discussed.
Koester, Roland,Synoradzki, Ludwik
p. 2850 - 2862
(2007/10/02)

Beitraege zur Chemie des Bors, 120. Tetraorganyldiborane(4): Darstellung und Stabilitaet
tert-Butylation of B2(OCH3)4 by LiC(CH3)3 proceeds via (CH3O)B-B(OCH3) (1) to give tri-tert-butylmethoxydiborane(4) (2).Tetraalkylation of B2(OCH3)4 is achieved by isopropyllithium; no reaction intermediates were found in this case.Al(C2H5)3 reacts with B2(OCH3)4 to give B2(C2H5)4 which is stable only below -30 deg C.On the other hand the CH3O group in 2 is replacable by CH3, and the CH3O groups in 1 by ethyl groups.Thus, product control by steric factors is evident.The thermal stability of tetraorganyldiboranes(4) is controlled by the steric screening of the boron atoms: tetraisopropyldiborane(4) decomposes slowly at room temperature, tetraethyldiborane(4) rapidly at -20 deg C.
Noeth, Heinrich,Pommerening, Hans
p. 3044 - 3055
(2007/10/02)

Monoalkylborane aus Alkyliden(triphenyl)phosphoranen und Boran; Kombination von Ylidreaktionen und Hydroborierung
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Bestmann, Hans Juergen,Suehs, Kurt,Roeder, Thomas
p. 1098 - 1100
(2007/10/02)

Carborane formation in alkyne-borane gas-phase systems. III. Flash reactions of small boranes
Thermally induced flash reactions of tetraborane(10) and pentaborane(11) with acetylene, methylacetylene, and dimethylacetylene have been studied, and the volatile products, consisting almost exclusively of parent or alkyl closed-cage carboranes and hydrocarbons, have been individually isolated and characterized. Both the total carborane yield and the relative yields of B3 and B4 carboranes are largest in reactions of dimethylacetylene and least in those of acetylene. Derivatives of 1,2-C2B3H5 are formed in significant amounts from alkylacetylenes but not from acetylene. The results are compared with previous work on borane-alkyne systems, particularly the electric-discharge and flash reactions of diborane with acetylene, and implications in regard to reaction pathways are discussed. The pentaborane(11)-dimethylacetylene system is exceptional; flash reactions are not observed in 1:1 mixtures, but a 2:1 alkyne:borane ratio results in flash reaction below room temperature in which largely noncarborane products are obtained.
Grimes, Russell N.,Bramlett, Christopher L.,Vance, R. Leonard
p. 55 - 58
(2008/10/08)