- Synthesis and characterization of novel covalent biphenyldiyl Sm(II) and Yb(II) complexes
-
Biphenylene reacts with activated Sm and Yb powders in ethers giving 2,2'-biphenyldiyl-Sm(II) and -Yb(II) complexes by opening of the C4 ring.They have been characterized by reactions with electrophiles such as the proton and dimethyldichlorosilane, and by 1H, 13C and 171Yb NMR measurements.The Yb complex can be obtained by reaction of 2,2'-dilithiobiphenyl with YbI2.Octamethylbiphenylene, the reduction potential of which is much more negative than that of biphenylene, does not react with Yb powder.In contrast, tricarbonyloctamethylbiphenylenechromium reacts with metal powder due to the presence of the electron-withdrawing Cr(CO)3 group.This suggests that an electron transfer from the metal precedes the opening of the cyclobutane ring.
- Chauvin, Yves,Marchal, Nathalie,Olivier, Helene,Saussine, Lucien
-
-
Read Online
- THE CHEMISTRY OF SILOLES. SYNTHESIS AND REACTIONS OF η6-CHROMIUM TRICARBONYL
-
η6-chromium tricarbonyl (II) was prepared by the reaction of 1-methyl-1-(trimethylsilyl)dibenzosilole with chromium hexacarbonyl.The reaction of II with methyllithium in THF gave η6-(1,1-dimethyldibenzosilacyclopentadiene)chromium tricarbonyl.Similar reaction of II with butyllithium, followed by oxidation, gave 1-butyl-1-methyldibenzosilole and 1,1-dibutyldibenzosilole, while reaction with (methyldiphenylsilyl)lithium under similar conditions afforded 1-methyl-4-(methyldiphenylsilyl)-1-(trimethylsilyl)dibenzosilole.
- Ishikawa, Mitsuo,Tabohashi, Tatsuru
-
-
Read Online
- Arsenic-Bridged Silafluorene and Germafluorene as a Novel Class of Mixed-Heteroatom-Bridged Heterofluorenes
-
Arsenic-bridged silafluorene and germafluorene were synthesized as a novel class of mixed-heteroatom-bridged heterofluorenes. Their structures, photophysical properties, and electronic natures were studied by experimental and computational means. The doubly-bridged biphenyl moieties were distorted from the reported singly-bridged ones. The intersystem crossing from the singlet excitation states to the triplet ones was enhanced by the arsenic-bridging structures, implying that bridging through an arsenic atom is favorable for phosphorescence.
- Sasaki, Hiroshi,Akioka, Ippei,Imoto, Hiroaki,Naka, Kensuke
-
-
Read Online
- Synthesis and characterization of dibenzannulated silole dianions. The 1,1-dilithiosilafluorene and 1,1'-dilithiobis(silafluorene) dianions
-
Stirring of 1,1-dichloro-SiFl (1), (SiFl, silafluorene) in THF with excess lithium for 1 h gave a dark green solution of 1,1-dilithio-SiFl (2) in high yield. The dark red solution of the intermediate 1,1'-dilithio-(SiFl)2 (3) was also observed from this reaction within 10 min. Treatment of 2 with excess trimethylchlorosilane gave the 1,1-bis(trimethylsilyl)-SiFl derivative (4) in 95% yield. Treatment of the dark red solution of 3 and 2 with excess methyliodide gave the 1,1'-dimethyl-bis(SiFl) (5) and 1,1-dimethyl-SiFl (6) derivatives in a 4:1 ratio. The upfield locations of the 29Si resonances of dianions 2 and 3 (-1.09 ppm and -39.25 ppm, respectively) are consistent with π-electron localization on the silicon atoms. (C) 2000 Elsevier Science Ltd.
- Choi,Boudjouk
-
-
Read Online
- TRICYCLIC HETEROCYCLES WITH BIFUNCTIONAL SILICON CENTERS
-
Condensation of the diorganometallic reagents, (o-MC6H4)2X (M = Li, MgCl) with HSiCl3 followed by reduction with LiAlH4 provides dibenzosilacycles, I (a, X = -; b, X = NMe; c, X = CH2; d, X = CH2CH2) with two exocyclic H-substituents, =SiH2.Conditions for the stepwise conversion of I to mixed bifunctional systems, =SiHX (II, X = Cl, Br; III, X = OR), and bifunctional derivatives, =SiX2 (IV, X = Cl; V, X = OR) were determined.Controlled halogenation of I to II was accomplished with one molar equivalent of SO2Cl2 or NBS although CCl4 in the presence of ClRh(PPh3)3 or PdCl2 results in slow monochlorination.The reaction of I with excess SOCl2 or SO2Cl2 converts I to III but the latter is faster and provides fewer side reactions.Conversion of I to IV with excess alcohols occurs in high yield with ClRh(PPh3)3 but in low yield with H2PtCl6.Controlled alcoholysis of I to III could not be achieved except with tBuOH.The dichlorides, IV, are methylated in high yield to VII, =SiMe2.Reaction of Ib with ClRh(PPh3)3 results in elimination of H2 and formation of disilanes as indicated by trapping reactions with alcohols (formation of Vb).
- Corey, Joyce Y.,Jonh, Christy S.,Ohmsted, Martha C.,Chang, Lihsueh S.
-
-
Read Online
- UNEXPECTED BEHAVIOR OF SILOLES TOWARD ORGANOLITHIUM REAGENTS
-
The reaction of 5-trimethylsilyl-5-methyldibenzosilole (I) with an excess of methyllithium in THF afforded 5,5-dimethyldibenzosilole (II) in quantitative yield.Treatment of I with an excess of butyllithium gave 5,5-dibutyldibenzosilole (III) quantitatively.Similar treatment of II with butyllithium in THF at room temperature gave III in almost quantitative yield, while treatment of III with methyllithium at reflux temperature gave II and 5-butyl-5-methyldibenzosilole in 10 and 40percent yield, in addition to 37percent of the starting III. 1,2,5-Tris(trimethylsilyl)-1-methyl-3,4-diphenylsilole also reacted with methyllithium to give 1,1-dimethyl-2,2,5-tris(trimethylsilyl)-3,4-diphenyl-1-silacyclopent-3-ene and 1,1-dimethyl-2,5-bis(trimethylsilyl)-3,4-diphenylsilole in 70 and 7percent yield.A five-coordinate silicon compound is proposed as an intermediate.
- Ishikawa, Mitsuo,Nishimura, Kunio,Sugisawa, Hiroshi,Kumada, Makoto
-
-
Read Online
- Rhodium-Catalyzed Synthesis of Benzosilolometallocenes via the Dehydrogenative Silylation of C(sp2)-H Bonds
-
Use of a rhodium catalyst with electron-rich and bulky chiral diphosphine ligands having C2-symmetry allowed efficient dehydrogenative silylation of the C(sp2)-H bond of ferrocenes leading to chiral benzosiloloferrocenes. The substra
- Murai, Masahito,Matsumoto, Koji,Takeuchi, Yutaro,Takai, Kazuhiko
-
-
Read Online
- A Catalytic SEAr Approach to Dibenzosiloles Functionalized at Both Benzene Cores
-
A general procedure for the catalytic preparation of dibenzosiloles functionalized at one or both benzene rings starting from readily available ortho-silylated biphenyls is reported. This method provides rapid access to silole building blocks substituted with chlorine atoms at both phenylene groups, thereby allowing catalytic access to directly polymerizable dibenzosiloles. Moreover, it is shown that, despite the involvement of highly electrophilic intermediates, a considerable range of Lewis-basic, for example, oxygen- and nitrogen-containing, functional groups is tolerated. The mechanism of this intramolecular electrophilic aromatic substitution (SEAr) proceeds through a sulfur-stabilized silicon cation, generated catalytically from the hydrosilane precursor.
- Omann, Lukas,Oestreich, Martin
-
-
Read Online
- 2,2′-Dilithiobiphenyl by direct lithiation of biphenylene
-
The reaction of biphenylene (1) with an excess of lithium powder (1:14 molar ratio) and a catalytic amount of DTBB (10 mol %) in THF at room temperature leads to the formation of the dilithiated species I by reductive opening of the four-membered ring. Further reaction of this intermediate with different electrophiles [Electrophile = H2O, D2O, Me3SiCl, t-BuCHO, Et2CO, n-Pr2CO, (CH2)5CO, Ph2CO and adamantanone] at 0 °C yields the corresponding products 2, after hydrolysis with water. Cyclisation of some representative examples of compounds 2 with H3PO4 gives the corresponding dibenzoxepines 3.
- Lillo, Victor J.,Gómez, Cecilia,Yus, Miguel
-
-
Read Online
- Synthesis of Dibenzosiloles through Electrocatalytic Sila-Friedel-Crafts Reaction
-
A novel electrocatalyzed method for the preparation of dibenzosiloles was developed through intramolecular C?H/Si?H dehydrogenative coupling strategy starting from biarylhydrosilanes. Both electro-donating and electro-withdrawing substitution groups were tolerated for this transformation, and the desired dibenzosilole products could be obtained in moderate to excellent yields. A sila-Friedel-Crafts reaction mechanism was proposed on the basis of previous literature and our controlled experiments. (Figure presented.).
- Han, Pan,Yin, Mengyun,Li, Haiqiong,Yi, Jundan,Jing, Linhai,Wei, Bangguo
-
supporting information
p. 2757 - 2761
(2021/04/16)
-
- Me3SiSiMe2(OnBu): a disilane reagent for the synthesis of diverse silacyclesviaBrook- And retro-Brook-type rearrangement
-
Herein, a readily available disilane Me3SiSiMe2(OnBu) has been developed for the synthesis of diverse silacyclesviaBrook- and retro-Brook-type rearrangement. This protocol enables the incorporation of a silylene into different starting materials, including acrylamides, alkene-tethered 2-(2-iodophenyl)-1H-indoles, and 2-iodobiaryls,viathe cleavage of Si-Si, Si-C, and Si-O bonds, leading to the formation of spirobenzosiloles, fused benzosiloles, and π-conjugated dibenzosiloles in moderate to good yields. Preliminary mechanistic studies indicate that this transformation is realized by successive palladium-catalyzed bis-silylation and Brook- and retro-Brook-type rearrangement of silane-tethered silanols.
- Xu, Yankun,Xu, Weiwei,Chen, Xinyang,Luo, Xiai,Lu, Haiyan,Zhang, Minghao,Yang, Xiumei,Deng, Guobo,Liang, Yun,Yang, Yuan
-
p. 11756 - 11761
(2021/09/22)
-
- Aromatic Metamorphosis of Thiophenes by Means of Desulfurative Dilithiation
-
A new mode of aromatic metamorphosis has been developed, which allows thiophenes and their benzo-fused derivatives to be converted to a variety of exotic heteroles. This transformation involves 1) the efficient generation of key 1,4-dianions by means of desulfurative dilithiation with lithium powder and 2) the subsequent trapping of the dianions with heteroatom electrophiles in a one-pot manner. Via the desulfurative dilithiation, the sulfur atoms of thiophenes are replaced also with a carbon–carbon double bond or a 1,2-phenylene for the construction of benzene rings.
- Kaga, Atsushi,Iida, Hirokazu,Tsuchiya, Shun,Saito, Hayate,Nakano, Koji,Yorimitsu, Hideki
-
supporting information
p. 4567 - 4572
(2021/02/12)
-
- Method for preparing 9-sila-fluoren derivative
-
The invention discloses a method forpreparinga 9-sila-fluoren derivative. The method forpreparingthe 9-sila-fluoren derivative comprises the steps thatsilane shown in a formula II is subjected to intramolecular dehydrocyclization reaction in the presence of a catalyst to obtain the 9-sila-fluoren derivative shown in a formula I; in the formula I and the formula II, R1 represents a substituent at the meta position and/or the para position on a benzene ring and isselected from one or more ofhydrogen, a substituted or unsubstituted alkyl group having 1 to 10 carbon atoms, a substituted or unsubstituted alkoxy group having 1 to 10 carbon atoms, a sulfonyl group, an ester group, and a halogen; R2 is selected from one or more ofthe substituted or unsubstituted alkyl group having the 1 to 10 carbon atoms and an aryl group; and R3 is selected from one or more of the hydrogen, the substituted orunsubstituted alkyl group having the 1 to 10 carbon atoms and the aryl group; and Ar is selected fromone or more of a substituted or unsubstituted phenyl group, a heterocyclic aryl group, and a fused ring aryl group. The method forpreparingthe 9-sila-fluoren derivative has the characteristicsthat the synthesis method iseasy to operate, adopted raw materials are easily obtained, a substrate is wide in applicability, the specific reaction systemis simple and efficient, and good atomic economy andenvironmental friendliness are achieved.
- -
-
Paragraph 0039-0053
(2019/10/29)
-
- Visible-Light Induced Radical Silylation for the Synthesis of Dibenzosiloles via Dehydrogenative Cyclization
-
A visible-light induced radical silylation to dibenzosiloles from biarylhydrosilanes is described. The products were obtained in satisfactory yields under mild and water/air compatible conditions, providing an efficient and practical method for the synthesis of difunctionalized siloles by using a cheap organic dye photocatalyst. The method is tolerated by a wide range of functional groups and has a broad substrate scope. Light/dark experiments and quantum yield measurements provided support for a photocatalytic pathway rather than a chain process. (Figure presented.).
- Yang, Chao,Wang, Jing,Li, Jianhua,Ma, Wenchao,An, Kun,He, Wei,Jiang, Chao
-
supporting information
p. 3049 - 3054
(2018/08/06)
-
- Organic electroluminescence compound with diphosphopentadiene condensed ring and synthesis method of compound
-
The invention discloses an organic electroluminescence compound with a diphosphopentadiene condensed ring and a synthesis method of the compound, and belongs to organophosphorus electroluminescence materials. The compound has a structure general formula as shown in a formula (I), wherein E is O or S, and a pi-conjugated group is phenyl or thiophene and the like. The compound can serve as a luminescent layer of an organic electroluminescence device to be applied to electroluminescence devices, luminescence properties of the device can be effectively changed by simply and chemically modifying phosphorus atoms and changing the pi-conjugated group, adjustment and control from blue light to yellow light are achieved, the compound is good in heat stability, natures of cis-trans-isomer devices are almost indistinguishable, the cis-trans-isomer devices has excellent charge injection and transmitting capacity, and the efficiency and the service lives of the corresponding organic electroluminescence devices can be remarkably improved.
- -
-
Paragraph 0026; 0039; 0040; 0041
(2018/10/19)
-
- Rhodium-Catalyzed Silylative and Germylative Cyclization with Dehydrogenation Leading to 9-Sila- and 9-Germafluorenes: A Combined Experimental and Computational Mechanistic Study
-
Stoichiometric amounts of oxidants are widely used as promoters (hydrogen acceptors) in dehydrogenative silylation of C?H bonds. However, the present study demonstrates that silylative and germylative cyclization with dehydrogenation can proceed efficiently, even without hydrogen acceptors. The combination of [RhCl(cod)]2 and PPh3 was effective for both transformations, and allowed a reduction in reaction temperature compared with our previous report. Monitoring of the reactions revealed that both transformations had an induction period for the early stage, and that the rate constant of dehydrogenative germylation was greater than that of dehydrogenative silylation. Competitive reactions in the presence of 3,3-dimethyl-1-butene indicated that the ratio of dehydrogenative metalation and hydrometalation was affected by reaction temperature when a hydrosilane or hydrogermane precursor was used. Further mechanistic insights of oxidant-free dehydrogenative silylation, including the origin of these unique reactivities, were obtained by density functional theory studies.
- Murai, Masahito,Okada, Ryo,Asako, Sobi,Takai, Kazuhiko
-
supporting information
p. 10861 - 10870
(2017/08/18)
-
- INTERMOLECULAR C-H SILYLATION OF UNACTIVATED ARENES
-
Reaction mixtures for silvlating arene substrates and methods of using such reaction mixtures to silyiate the arene substrates are provided. Exemplary reaction mixtures include the arene substrate, a liganded metal catalyst, a hydrogen acceptor and an organic solvent. The reaction conditions allow for diverse substituents on the arene substrate.
- -
-
Paragraph 00128
(2015/03/28)
-
- 9-Silafluorenes via base-promoted homolytic aromatic substitution (BHAS) - The electron as a catalyst
-
Transition-metal-free intramolecular radical silylation of 2-diphenylsilylbiaryls via base-promoted homolytic aromatic substitution (BHAS) to give 9-silafluorenes is reported. 2-Diphenylsilylbiaryls are readily prepared, and cross dehydrogenative silylation occurs with tert-butylhydroperoxide (TBHP) as a cheap stoichiometric oxidant in the presence of a small amount of tetrabutylammonium iodide (TBAI) as an initiator. These cyclizations are catalyzed by the electron.
- Leifert, Dirk,Studer, Armido
-
supporting information
p. 386 - 389
(2015/01/30)
-
- Rhodium-catalyzed dehydrogenative germylation of C-H bonds: New entry to unsymmetrically functionalized 9-germafluorenes
-
Rhodium-catalyzed dehydrogenative germylation leading to unsymmetrically functionalized 9-germafluorenes via Ge-H and C-H bond activation is described. Despite the significant achievements made in dehydrogenative functionalization of C-H bonds, only a limited number of examples with the fourth-row atom-H bonds have been reported. The current method enabled the synthesis of various 9-germafluorene derivatives, including tetracyclic as well as donor-acceptor substituted germoles, which may be useful for electronic device applications.
- Murai, Masahito,Matsumoto, Koji,Okada, Ryo,Takai, Kazuhiko
-
p. 6492 - 6495
(2015/02/19)
-
- B(C6F5)3-catalyzed synthesis of benzofused-siloles
-
The dehydrosilylation of 2-(SiR2H)-biphenyls catalyzed by B(C6F5)3 and a weak base forms silafluorenes with H2 as the only byproduct. Attempts to extend this approach to synthesize siloles derived from 2,2′-bithiophenes and N-Me-2-Ph-indole resulted in competing reactivity, including protodesilylation. B(C6F5)3 also catalyzed the one-pot, two-step formation of silaindenes from aryl-alkynes by alkyne trans-hydrosilylation, followed by an intramolecular Sila-Friedel-Crafts reaction facilitated by a weak base.
- Curless, Liam D.,Ingleson, Michael J.
-
supporting information
p. 7241 - 7246
(2015/03/03)
-
- Rhodium-catalyzed carbon-silicon bond activation for synthesis of benzosilole derivatives
-
A rhodium-catalyzed coupling reaction of 2-trimethylsilylphenylboronic acid with internal alkynes is developed for the synthesis of 2,3-disubstituted benzosilole derivatives. A range of functional groups, encompassing ketones, esters, amines, aryl bromides, and heteroarenes, are compatible, which provides rapid access to diverse benzosiloles. Sequential 2-fold coupling enables modular synthesis of asymmetrically substituted 1,5-dihydro-1,5-disila-s-indacene, a π-extended molecule of interest in organic electronics. In terms of the mechanism, the reaction involves cleavage of a C(alkyl)-Si bond in a trialkylsilyl group, which normally requires extremely harsh conditions for activation. Mechanistic studies, including effects of substituents, reveal that C-Si bond cleavage does not proceed through a hypercoordinated silicon species, but rather through a rhodium-mediated activation process. The potential use of the reaction in catalytic asymmetric synthesis of Si-chiral benzosiloles is also demonstrated.
- Onoe, Masahiro,Baba, Katsuaki,Kim, Yoonjoo,Kita, Yusuke,Tobisu, Mamoru,Chatani, Naoto
-
p. 19477 - 19488
(2013/02/21)
-
- Construction of benzosiloles, six- and eight-membered silacyclic skeletons, via a Pd-catalyzed intramolecular Mizoroki-Heck reaction of vinylsilanes
-
A variety of silacycles including benzosiloles, six- and eight-membered silacyclic skeletons, were efficiently synthesized via a Pd-catalyzed intramolecular Mizoroki-Heck reaction of vinylsilanes.
- Ouyang, Kunbing,Liang, Yun,Xi, Zhenfeng
-
p. 4572 - 4575
(2012/11/07)
-
- Palladium-catalyzed synthesis of benzosilolo[2,3- b ]indoles via cleavage of a C(sp3)-Si bond and consequent intramolecular C(sp 2)-Si coupling
-
An efficient process involving Pd-catalyzed selective cleavage of a C(sp3)-Si bond and consequent intramolecular C(sp2)-Si coupling has been developed, affording benzosilolo[2,3-b]indoles as a new type of silicon-bridged polyheteroarene in excellent yields. Aldehyde was found for the first time to be able to promote the efficiency of the catalytic process remarkably.
- Liang, Yun,Zhang, Shaoguang,Xi, Zhenfeng
-
p. 9204 - 9207
(2011/08/06)
-
- ANTHRACENE DERIVATIVES AND ORGANIC ELECTROLUMINESCENT DEVICE USING SAME
-
Provided are a novel anthracene derivative and an organic light-emitting device using the same, and more particularly, an anthracene derivative having a core (e.g., an indenoanthracene core) where an anthracene moiety with excellent device characteristics is fused with a fluorene moiety or the like with excellent fluorescent properties, wherein an aryl group is introduced at the core, and an organic light-emitting device using the anthracene derivative, which is enhanced in efficiency, operating voltage, lifetime, etc.
- -
-
-
- Rhodium-catalyzed synthesis of silafluorene derivatives via cleavage of silicon-hydrogen and carbon-hydrogen bonds
-
The rhodium-catalyzed synthesis of silafluorenes from biphenylhydrosilanes is described. This highly efficient reaction proceeds via both Si-H and C-H bond activation, producing only H2 as a side product. Using this method, a ladder-type bis-silicon-bridged p-terphenyl could also be synthesized.
- Ureshino, Tomonari,Yoshida, Takuya,Kuninobu, Yoichiro,Takai, Kazuhiko
-
supporting information; experimental part
p. 14324 - 14326
(2010/12/19)
-
- Rhodium-catalyzed coupling of 2-silylphenylboronic acids with alkynes leading to benzosiloles: Catalytic cleavage of the carbon-silicon bond in trialkylsilyl groups
-
(Chemical Equation Presented) The reaction of 2-(trimethylsilyl) phenylboronic acid with alkynes in the presence of a rhodium catalyst affords benzosilole derivatives. The arylvinylrhodium intermediate undergoes formal substitution at a silicon center, resulting in the cleavage of a robust silicon-methyl bond in the trimethylsilyl group.
- Tobisu, Mamoru,Onoe, Masahiro,Kita, Yusuke,Chatani, Naoto
-
supporting information; experimental part
p. 7506 - 7507
(2009/10/17)
-
- Modular approach to silicon-bridged biaryls: Palladium-catalyzed intramolecular coupling of 2-(arylsilyl)aryl triflates
-
(Chemical Equation Presented) Bridge of Si: Intramolecular direct arylation of 2-(arylsilyl)aryl triflates is catalyzed smoothly by Pd(OAc) 2/PCy3 in the presence of Et2NH in dimethylacetamide (DMA), giving rise to the corresponding silicon-bridged biaryls in good to excellent yields. The new approach has led to the synthesis of a silicon-bridged 2-phenylindole (see scheme) that exhibits blue photoluminescence in the solid state with extremely high quantum yields.
- Shimizu, Masaki,Mochida, Kenji,Hiyama, Tamejiro
-
body text
p. 9760 - 9764
(2009/05/30)
-
- Selective monolithiation of dibromobiaryls using microflow systems
-
(Chemical Equation Presented) Selective monolithiation of dibromobiaryls, such as 2,2′-dibromobiphenyl, 4,4′-dibromobiphenyl, 2,7-dibromo-9,9-dioctylfluorene, 2,2′-dibromo-1,1′-binaphthyl, and 5,5′-dibromo-2,2′-bithiophene, with 1 equiv of n-butyllithium followed by the reaction with electrophiles was achieved using a microflow system by virtue of fast micromixing and precise temperature control. Sequential introduction of two different electrophiles based on this method was also achieved using a microflow system composed of four micromixers and four microtube reactors.
- Nagaki, Aiichiro,Takabayashi, Naofumi,Tomida, Yutaka,Yoshida, Jun-ichi
-
supporting information; experimental part
p. 3937 - 3940
(2009/06/18)
-
- Halogen-metal exchange in 1,2-dibromobenzene and the possible intermediacy of 1,2-dilithiobenzene
-
(Chemical Equation Presented) The one-step high-yield synthesis of 1,2-bis(trimethylsilyl)-benzene from 1,2-dibromobenzene using tert-butyllithium and trimethylsilyltriflate is reported. A mechanistic investigation shows that 1,2-dilithiobenzene is not an intermediate in this reaction; the coexistence of trimethylsilyltriflate and tert-butyllithium at very low temperatures allows a sequence of bromine-lithium exchange and subsequent derivatization reactions to operate.
- Bettinger, Holger F.,Filthaus, Matthias
-
p. 9750 - 9752
(2008/03/17)
-
- Reactions of dilithiobutadienes with monochlorosilanes: Observation of facile loss of organic groups from silicon
-
Reactions of 1,4-dilithiobutadienes (from 1,4-diiodo-1,2,3,4- tetraethylbutadiene (1) and 2,2′-dibromobiphenyl (7) with t-BuLi) with Me3SiCl gave siloles (3 and 9a) as the major products. No evidence for a disilylated butadiene was obtained. Use of higher molecular weight chlorosilanes ((allyl)Me2SiCl, BnMe2SiCl, and PhMe 2SiCl) with dibromide 7 gave dimethylsilole 9a and a silane (10a, 10b, or 10c) resulting from trapping of the organic group by the chlorosilane.
- Hudrlik, Paul F.,Dai, Donghua,Hudrlik, Anne M.
-
p. 1257 - 1264
(2007/10/03)
-
- Cleavage of C-Si bond by intramolecular nucleophilic attack: Lithiation-promoted formation of siloles from 1-bromo-4-trisubstituted silyl-1,3-butadiene derivatives
-
Lithiation of 1-bromo-4-trisubstituted silyl-1,3-butadiene derivatives with t-BuLi afforded substituted siloles in high yields. Cleavage of one of the three C-Si bonds took place via intramolecular nucleophilic substitution. Selective cleavage was observed when the silyl group possessed different substituents. Results showed that vinyl and phenyl substituents on Si were substituted much more easily than methyl groups, whilst a methyl group was exclusively deleted from an i-Pr-SiMe2 moiety.
- Wang, Zhihui,Fang, Hongyun,Xi, Zhenfeng
-
p. 499 - 501
(2007/10/03)
-
- Structure and chemistry of 1-silafluorenyl dianion, its derivatives, and an organosilicon diradical dianion
-
1-Silafluorene dianion was synthesized by potassium reduction of 1,1-dichloro-1-silafluorene in refluxing THF. The X-ray structure of 1,1-dipotassio-1-silafluorene (3b) shows C-C bond length equalization in the five-membered silole ring and C-C bond length alternation in the six-membered benzene rings, indicating aromatic delocalization of electrons in the silole ring. The downfield 29Si chemical shift at 29.0 ppm and theoretical calculations also support electron delocalization in the silole ring of 3b. Dianion salt 3b underwent nucleophilic reactions with Me3SiCl and EtBr to form the corresponding disubstituted products. Benzaldehyde underwent reductive coupling in the presence of 3b. Slow oxidation of 3b yielded 1,1′dipotassio-1,1′-bis(silafluorene) (16). The X-ray structure and 29Si chemical shift (-38.0 ppm) of 16 indicate localized negative charges at the silicon atoms and no aromatic character. Heating a DME/hexane solution of 3b in the presence of 18-crown-6 led to a novel diradical dianion salt.
- Liu,Stringfellow,Ballweg,Guzei,West
-
-
- Lithium-2-2'-biphenyldiyltrimethylsilicat: erstmalige Beobachtung von Pentaorganosilicaten
-
Keywords: Lithiumverbindungen; NMR-Spektroskopie; Siliciumverbindungen; Substitutionen
- Keijzer, Adrianus H. J. F. de,Kanter, Franciscus J. J. de,Schakel, Marius,Schmitz, Robert F.,Klumpp, Gerhard W.
-
p. 1183 - 1184
(2007/10/03)
-
- NEW PRECURSORS TO SILAFLUORENES
-
Conversion of 2,2'-dibromo-4,4'-di-t-butylbiphenyl and o-bromo-o'-chlorobiphenyl to organometallic reagents suitable for reaction with Me2SiCl2 to produce silafluorene has been developed.
- Corey, Joyce Y.,Chang, Lihsueh S.
-
-
- PHOTOCHEMISTRY OF DIBENZO-1,1,2,2,3,3-HEXAMETHYL-1,2,3-TRISILACYCLOHEPTA-4,6-DIENE AND THE GERMANIUM ANALOG. GENERATION OF TETRAMETHYLDISILENE BY FREE-RADICAL DISPROPORTIONATION AND THE FIRST SPECTROSCOPIC DETECTION OF DIMETHYLGERMYLENE
-
Photolysis of the title compound afforded silafluorene and dibenzo-1,2-disilacyclohexadiene as primary photoproducts.Two reactive intermediates, tetramethyldisilene and dimethylsilylene, were trapping.The dimethylgermylene, derived from germanium analog, was first observed by electronic spectra.
- Sakurai, Hideki,Sakamoto, Kenkichi,Kira, Mitsuo
-
p. 1379 - 1382
(2007/10/02)
-
- PHOTOCHEMICAL REACTION OF DIBENZOTETRAMETHYLDISILACYCLOHEXADIENE THROUGH CHARGE-TRANSFER COMPLEX
-
The reaction of dibenzo-1,1,2,2-tetramethyl-1,2-disilacyclohexadiene with tetracyanoethylene under illumination with a sodium lamp gave dibenzo-1,1-dimethyl-1-silacyclopentadiene as a silylene extrusion compound through a charge-transfer complex.
- Sakurai, Hideki,Sakamoto, Kenkichi,Kira, Mitsuo
-
p. 1213 - 1214
(2007/10/02)
-
- SIMPLIFIED APPROACH TO SILAANTHRONES AND DISILAANTHRACENES
-
An improved synthesis of bis(o-chlorophenyl)methylsilane is reported from reaction of a mixture of o-BrC6H4Cl and MeSiHCl2 with Mg shavings in THF.The diarylsilanes, (o-ClC6H4)2SiMeR (R = H, Me) could be converted to diGrignard reagents with Mg prepared by the Rieke method but not from commercial Mg (shavings or mesh).The diorganomatallic reagents generated from (o-XC6H4)2SiMeR (R = H, Me) are used to prepare disilaanthracenes or silaanthrones.A new spiro derivative, bis(dimethyl-o,o'-diphenylsilyl)spirosilane, is obtained on addition of HSiCl3 to the diGrignard reagent generated from (o-ClC6H4)2SiMe2.When gaseous CO2 is added to the dilithio reagent formed from (o-BNrC6H4)2SiMe2, silaanthrone is produced which provides a new route to the silaanthracene framework.Aspects of this new ring closure route are described.
- Corey, J. Y.,McCarthy, W. Z.
-
p. 319 - 326
(2007/10/02)
-
- CHEMISTRY OF SILOLES. THE REACTIONS OF SILOLES WITH ORGANOLITHIUM REAGENTS
-
The chemical behaviour of siloles toward various organolithium reagents in THF has been investigated.The reaction of 1-methyl-1-(trimethylsilyl)-, 1-phenyl-1-(trimethylsilyl)- and 1,1-bis(trimethylsilyl)dibenzosilole(I, II and III) with a large excess of an alkyllithium such as methyllithium or butyllithium afforded 1,1-dialkyldibenzosiloles in quantitative yields.Treatment of I with an excess of phenyllithium gave a mixture of 1-methyl-1-phenyl- and 1,1-diphenyldibenzosilole quantitatively, while with an excess of tert-butyllithium, I afforded 1,1-dimethyl and 1-tert-butyl-1-methyldibenzosilole in low yield.Similar treatment of I and II with 1 equiv. of methyl- or butyl-lithium yielded a mixture of the corresponding mono- and dialkyl-substituted dibenzosiloles. 1-Methyl-3,4-diphenyl-1,2,5-tris(trimethylsilyl)silole reacted with methyllithium in THF to give 1,1-dimethyl-3,4-diphenyl-2,2,5-tris(trimethylsilyl)silole.Similarly, both 2,4-diphenyl-1,1,3,5-tetrakis(trimethylsilyl)silole and 4,5-diphenyl-1,1,2,3-tetrakis(trimethylsilyl)silole with methyllithium afforded two isomers of 1-methyl-2,4-diphenyl-1,2,3,5-tetrakis(trimethylsilyl)-1-silacyclopent-3-ene in a ratio of 3:2 in high yields.
- Ishikawa, Mitsuo,Tabohashi, Tatsuru,Sugisawa, Hiroshi,Nishimura, Kunio,Kumada, Makoto
-
p. 109 - 120
(2007/10/02)
-
- REGIOSELECTIVE DIMETALLIERUNG VON AROMATEN. BEQUEMER ZUGANG ZU 2,2'-DISUBSTITUIERTEN BIPHENYLDERIVATEN
-
Lithiation of biphenyl with 2.4 mol of n-butyllithium in the presence of TMEDA led directly to the 2,2'-dilithio derivative (I) in modest, but preparatively useful yields.I, in turn, was converted to a variety of products.The activation of the 2'-position of 2-lithiobiphenyl was shown directly by a separate experiment.MNDO calculations indicate stabilization in I by double bridging and in 2-lithiobiphenyl by intramolecular ? interaction of Li with the o-phenyl group.Similar interactions in substitution transition states rationalize the specificity of the reactions observed.
- Neugebauer, Wolfgang,Kos, Alexander J.,Schleyer, Rague
-
p. 107 - 118
(2007/10/02)
-