Benzenes with silanes

Both PMPPIC and PS contain benzene rings, and their delocalized II electrons provide strong interactions. As a result, that there is an adhesion between PMPPIC and PS (Fig. 8). Comparing both methods, treatment with silanes or treatment with isocyanates, it is obvious that the isocyanatic treatment is more effec-... 

To prepare multifunctionalized symmetric organosilicon compounds by the polyalkylation of benzene. (2-chloroethyi)trichlorosilane and (3-chloropropyl)tri-chlorosilane were reacted with benzene. Polyalkylations of benzene with (2-chloroethyl)silane and (3-chloropropyl)silane were carried out in the presence of aluminum chloride catalyst at a reaction temperature of 80 C. The reaction of benzene with excess (2-chloroethyI )trichlorosilanes afforded pcralkylated product, hexakis(2-(trichlorosilyl)ethyl)benzene in good yield (70%). ... 

The alkylation of benzene with ((w,a -dichloroalkyl)silanes was also studied in the presence of aluminum chloride catalyst. The alkylation gave diphenylated products, (w.w-diphenylalkyl)chlorosilanes in fair to good yields (Eq. (12)). 

In the alkylation of benzene with (dichloroalkyl)chlorosilanes in the presence of aluminum chloride catalyst, the reactivity of (dichloroalkyl)silanes increases as the spacer length between the C—Cl and silicon and as the number of chloro-groups on the silicon of (dichloroalkyl)chlorosilanes decreases as similarly observed in the alkylation with (cD-chloroalkyl)silanes. The alkylation of benzene derivatives with other (dichloroalkyl)chlorosilanes in the presence of aluminum chloride gave the corresponding diphenylated products in moderate yields.Those synthetic data are summarized in Table XI. 

The results obtained from the alkylation of benzene with (trichloromethyl)silanes are summarized in Table XIV. 

A.s. shown in Table XV, the decomposition of (triphenylmethyl)methyldichloro-silane did not occur at room temperature, but occurred at the reflux temperature of benzene to give (diphenylmethyl)methyldichlorosilane in 10 and 20% yields after I and 2 h reaction periods. The results indicate that the decomposition occurs in the alkylation reaction conditions of benzene with (trichloromethyl)chlorosilanes a.s observed in the decomposition of tetraphcnylmethane to triphenylmethane. ... 

The addition of silyl radicals to double bonds in benzene or substituted benzenes (Reaction 5.2) is the key step in the mechanism of homolytic aromatic substitution with silanes [8,9]. The intermediate cyclohexadienyl radical 2 has been detected by both EPR and optical techniques [21,22]. Similar cyclohex-adienyl-type intermediates have also been detected with heteroaromatics like furan and thiophene [23]. 

Pt2(dba)3-catalyzed reaction of a series of substituted benzenes with o-bis(dimethylsilyl)benzene.95 This intriguing process gives high yields of o-(aryldimethylsilyl)(dimethylsilyl)benzenes for a variety of arenes, but appears limited to this particular silane [Eq. (33)]. 

Copper-catalyzed reactions of [(tosylimino)iodo]benzene with unsaturated compounds sometimes lead to tosylamidation. Examples include conversions of silyl enol ethers to a-tosylamido ketones [173], and tosylamidation of allylic silanes with loss of the silyl group [190] (Scheme 69). 

The dibenzo derivative of a cyclic acetylenic silane 96 was synthesized by mono-deprotonation of 1,2-diethynyl-benzene with 1 equiv of lithium hexamethyldisilazide (LiHMDS) followed by treatment with 0.5equiv of dichlor-odiphenylsilane (formation of 95). A repeat of the deprotonation step, followed by silylation cycle, gave 96 in 77% yield after column chromatography (Scheme 19). One-step preparation of 96 using 2 equiv of base and 2 equiv of the silylation agent also yielded the desired product, however, the yield was 50% of those of the previous method... 

Reactions of thiol esters with the three most commonly used reagents - tri-butylstannane,tris(trimethylsilyl)silane (TTMSS),and allyltributylstannane -were conducted using AIBN as an initiator. The reaction of 36 with 1.3 equiv of Bu3SnH in refluxing benzene with AIBN for 1 h led to complete consumption of the substrate and clean formation of the cyclization and reduction products (39 and 40, respectively, see Fig. 3) in a ratio of 96 4. As anticipated, dihydro-benzothiophene 41 was also formed in this reaction. It is worth noting that 40... 

Transition-metal-silyl complexes are also formed by the reactions of metal-alkyl complexes with silanes to form free alkane and a metal-silyl complex. Two examples are shown in Equations 4.114 and 4.115. ° The synthesis of silyl complexes by this method has been accomplished with both early and late transition metal complexes. The formation of metal-silyl complexes from late-metal-alkyl complexes resembles the hydrogenolysis of metal-alkyl complexes to form metal hydrides and an alkane. The mechanisms of these reactions are discussed in Chapter 6. In brief, these reactions with late transition metal complexes to form silyl complexes typically occur by a sequence of oxidative addition of the silane, followed by reductive elimination of alkane. An example of this is shown in the coupling of 1,2-bis-dimethylsilyl benzene with a dimethyl platinum(II) complex (Equation 4.114). Similar reactions occur with d° early metal complexes by a a-bond metathesis process that avoids these redox events. For example, the reaction of Cp ScPh with MesSiH, has been shown to proceed through this pathway (Equation 4.115). ... 

Metal oxide electrodes have been coated with a monolayer of this same diaminosilane (Table 3, No. 5) by contacting the electrodes with a benzene solution of the silane at room temperature (30). Electroactive moieties attached to such silane-treated electrodes undergo electron-transfer reactions with the underlying metal oxide (31). Dye molecules attached to sdylated electrodes absorb light coincident with the absorption spectmm of the dye, which is a first step toward simple production of photoelectrochemical devices (32) (see Photovoltaic cells). 

Benzhydryloxy ethoxy diphenyl silane (2). To a solution of benzoyl triphenylsilane 1 (2.5 g, 6 9 mmol) in benzene (25 mL) was added a solution of sodium ethoxide in ethanol (2 mL, 0 S mmol). The solution changed colour and after 11 min laded airmst completely. The solution was washed with water and the solvent removed in vacuum. The oily residue was dissolved in hot ethanol (15 mL) and cooled to give 2 (2 1 g, 74%), np 67-75 C Recrystallizatlon from ethanol gave 1 8 g (64%). mp 77-78,C... 

The titanium(IV) chloride catalyzed addition of allylic silanes to (E)-(2-nitroethenyl)benzene affords y,<5-unsaturated nitronates which, on treatment with low valent titanium species [generated in situ from titanium(IV) and zinc], give y,<5-unsaturated nitriles. For example, [(Zs)-2-butenyl]-(dimethyl)phenylsilane underwent reaction with ( )-(2-nitroethenyl)benzene to give 3-methyl-2-phenyl-4-pentenenitrile in 65 % yield as a 3 1 mixture of diastereomers of unassigned configuration22. 

Another common deposition system is based on the reaction of silane with a hydrocarbon such as propane or benzene in the following simplified reactions ... 

The substituent effect of vinylsilanes is similar to that of allylsilanes. The reactivity of vinylsilanes increased as the number of chlorine atoms on the silicon increased, but decreased as the number of methyl groups increased. However, vinyltrimethylsilane does not react with benzene to give alkylated products. " In the aluminum chloride-catalyzed alkylation of arenes with allylsilanes or vinylsilanes, one or more chlorine substituents on the silicon atom of silanes are required. 

The alkylation of halogen-substituted benzenes such as fluorobenzene and dichlorobenzenes with other (dichloroalkyl)silanes in the presence of aluminum chloride catalyst afforded isomeric mixtures of the corresponding (dihalogen-substituted phenyl)alkylsilanes in moderate yields (Eq. (13)). These results are summarized in Table Xll. 

Alkyl.aiion Condiitons of Benzene Derivai ives (X x -CaHj) WITH (Dichloroalkyl)silanes (CLRSitCiiHsn-iCh) and Yields OE Products ((X X C(,H4)2H2 -iC SiRCl2)... 

When (trichloromethyl)silanes reacted with excess benzene in the presence of aluminum chloride at reflux temperature, (triphenylmethyl)silanes were obtained as the major products along with (diphenylmethyl)silanes as minor products (Eq. (17)). Excess benzene was used to avoid the production of polymeric materials due to polyalkylation of one phenyl group. 

---