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The facile hydrostannation of diynes and triynes with tributyltin hydride was achieved. The hydrostannation product readily underwent the Stille cross-coupling reaction with a variety of aryl bromides. The copper-mediatedStille cross-coupling of 1,3,5-tris[(E)-2-(tributylstannyl)vinyl]benzene with (E)-β-iodostyrene afforded the conjugated diene.

The Rh(I)-catalyzed hydroboration of a variety of aromatic diynes and a triyne afforded bis(boryl)- and tris(boryl)vinyl products. The hydroboration products underwent Suzuki cross-coupling reactions with a variety of substrates containing chromophore units to give fluorescent dye-substituted products. The hydroboration product also reacted with dibromoarenes to afford an oligomer with a vinylene unit along the oligomer backbone.

In situ tetrakis(triphenylphosphine)palladium appeared to be a very efficient catalyst for dehydrogenative double silylation of bis- and tris(dichlorosilyl)methanes with acetylenes to produce 1,1,3...

A series of trisilaalkanes has been prepared in high yields by the direct reaction of -chloromethylsilanes with metallic silicon in the presence of copper catalyst using the stirred reactor equipped with a spiral band agitator at the carefully controlled temperature between and Disilaalkane compounds were obtained as the minor products. Cadmium was found to be a good promotor for the reactions, while zinc was an inhibitor.

The photochemical reactions of 2-R-2-phenyl[5,6: 7,8]dibenzo-2-silabicyclo[2.2.2]octanes (R = Ph, 1, R = Me, 5) in cyclohexane have been studied in the presence or absence of trapping agents such as methanol and methoxytrimethylsilane. The photolysis of 1 in the presence of methanol gave 9-(1,1-diphenylmethoxysilyl-3,3-dimethylbutyl)-9,10-dihydroanthracene as the major product and the methanol adduct of 1,1-diphenyl-2-neopentylsilene as the minor product. When trimethylmethyoxysilane was used as the trap, the silene adduct was only isolated in small quantity and no 9,10-disubstituted anthracene product was obtained. The photolysis of pure Z-5 or E-5 in the absence of trapping agent gave Z - E photoisomerization products and polymeric products. During the photolysis a constant ratio of Z-5 and E-5 was never observed because the formation of high molecular weight products was faster than isomerization. The major product of photolysis of pure E-5 or Z-5 in the presence of methanol or deuterated methanol was SS(RR), 6, and RS(SR), 6′, respectively, at early stages of the reaction but the other diastereomer was produced also as the photolysis proceeded. Photoisomerization of the diastereomers 6 and 6′ also occurred. The 1,6-biradical intermediates formed from Z- and E-5 retain their asymmetry at the silicon atom prior to the abstraction of methoxy group from methanol, but not at carbon.

Novel polysilamethylenosilanes (PSMS) were prepared by Wurtz type co-condensation of various mixtures of 2,4,4,6-tetrachloro-2,6-dimethyl-2,4,6-trisilahept ane (TSH) and dimethyldichlorosilane (D). When TSH was incorporated more than 25 mole%, PSMS polymers were soluble in common organic solvents probably due to the polycarbosilane linkage brought from TSH. The molecular weights of the polymer were measured by gel permeation chromatography and showed higher molecular weight with high TSH content. The thermal gravimetric residues increased as TSH contents increased. These properties suggested that PSMS polymers could be useful as ceramic precursors for silicon carbide.

Allyltrimethylsilane reacts with phenylalkynes in the presence of aluminium chloride catalyst under mild conditions to afford silylphenyldienes in moderate yield. In this allylsilylation reaction, the silyl group adds regioselectively to the terminal carbon and the allyl group to the inner carbon of the triple bond. The allylsilylation of phenylacetylene gives the allylsilylated product having the silyl and allyl groups in the cis -position, while diphenylacetylene gives the trans product. The allylic inversion was also observed in the allylsilylation with the stereohomogeneous ( Z )-crotyltrimethylsilane. These results are consistent with the initial formation of trimethylsilyl cation intermediate and a stepwise process of allylsilylation.

Reactions of diallylsilanes with allyltrimethylsilane in the presence of aluminum chloride as a catalyst resulted in intramolecularly cyclized allylsilylation products of trans- and cis-3-allyl-1,1-dimethyl-5-((trialkylsilyl)methyl)-1-silacyclohexanes in good yields. The reaction proceeded faster and gave better yields with the incorporation of chlorotrimethylsilane in the aluminum chloride catalyst.

Allyltrimethylsilane reacts with simple conjugated dienes in the presence of aluminum chloride catalyst to give stereoselective [3 + 2] cycloadducts of trans-vinylcyclopentanes in 29−72% yields at ...

A series of six-membered ring organosilicon compounds, 1-aryl-1-(1H-1,2,4-triazol-1-yl)alkyl-1-silacyclohexanes 3a-c, have been synthesized by four-step reactions starting from 1-(chloroalkyl)trichlorosilanes. Their fungicidal activities were tested in in vitro for ten fungi and in vivo assay for four fungi occurring in rice, barley, tomato, and etc. and compared with the flusilazole. Especially, 1-p-fluorophenyl-1-[1-(1H-1,2,4-triazol-1-yl)alkyl]-1-silacyclohexanes (3a, alkyl=methyl; 3b, alkyl=ethyl) showed good fungicidal activity with broad spectrum close to the flusilazole in in vivo assay.

The Grignard coupling reaction of bis(chloromethyl)diorganosilanes [(ClCH2)2SiR1R2: R1 = R2 = Me, la; R1 = Me, R2 = Ph, lb; R1 = R2 = Ph, lc] with diorganodichlorosilanes [(Cl2SiR3R4: R3 = R4 = Me, 2a; R3 = Me, R4 = Ph, 2b; R3 = R4 = Ph, 2c] at THE reflux temperature gave the intermolecular C-Si coupling product of 1,1,3,3-tetraorgano-1,3-disilacyclobutanes 3a-f in poor to moderate yields ranging from 7% to 50% along with polydiorganosilapropanes. The cyclization reaction of la-c with methyl-substituted dichlorosilanes 2a, b gave 1,3-disilacyclobutanes 3a-c, e, d in moderate yields (42-50%), while the same reaction with dichlorodiphenylsilane (2c) to 1,3-disilacyclobutanes 3d, f resulted in low yield (7-18%) probably due to the steric hindrance of two-phenyl groups on the silicon of 2c.

The structure-reactivity relationship of titanium complexes CySi(HNBut)2TiCl2 (1) (CySi = silacyclobutane, silacyclopentane, silacyclopentene, and silacyclohexane) stabilized by a series of cyclic silyldiamide ligands has been studied. The crystallographic results establish that steric interactions between the silacycloalkyl and tert-butyl groups influence the C(But)-N-Ti angles and, hence, the steric environment at titanium. The compounds 1 were further investigated as potential catalysts for the polymerization of ethylene. While sterically less demanding silacyclobutyl and -pentyl diamide complexes (1a and 1b) exhibit low ethylene polymerization activity (3.9 ∼5.8 kg PE molcat −1h−1) in the presence of methylalumoxane, highly puckered silacyclohexyl diamide complex 1e shows better activity (10 kg PE molcat −1 h−1) for the ethylene polymerization when it is activated with MAO.

Terminal and activated internal olefins such as 1-hexene, 1-decene, styrene, p-methylstyrene, 1-phenylprop-l-ene, and stilbene reacted with a mixture of HSiCl3 and SiCl4 in the presence of Bu4PCl at 180 °C for 4−16 h to give the α,β-bis(trichlorosilyl)alkanes 2 (70−85%) and alkyltrichlorosilanes 3 (10−21%). However, the reactions of the unactivated internal olefins 3-hexene and cyclopentene for 32 h under the same conditions gave 41% and 85% consumption and produced the bis-silylation compounds 2 in 12 and 43% yields along with hydrosilylation products 3 in 24 and 28% yields, respectively.

Allyl(chloromethyl)diorganosilanes [CH2CHCH2SiR1R2(CH2Cl), R1 = Me, Ph; R2 = Me, Ph, p-ClC6H4] in the presence of aluminum chloride undergo an allyl rearrangement reaction with allylic inversion to afford (3-butenyl)diorganochlorosilanes at room temperature. When allyltrimethylsilane was added to the reactions, the intermediate was trapped to give 1,1-dimethyl-3-(2-trimethylsilylmethyl-4-pentenyl)silacyclopentane (4) along with 3-(butenyl)dimethylchlorosilane in 40% and 18% yields, respectively. The formation of 4 can be explained by the addition reaction of allyltrimethylsilane to 1-silacyclopent-3-yl cation produced by the intramolecular cyclization of (allyl)silylmethyl cation intermediate derived from the interaction of the chloromethyl group with aluminum chloride catalyst, followed by desilylation reaction.

The dehydrochlorinative Si−C coupling reactions of various primary and secondary alkyl chlorides with hydridochlorosilanes in the presence of tetrabutylphosphonium chloride as catalyst gave the coupling products with elimination of HCl as a gas. Coupling reactions of activated alkyl chlorides such as benzyl chlorides proceeded at 130 °C, while unactivated organic chlorides such as silylalkyl chlorides and secondary alkyl chlorides required higher reaction temperatures of 150 or 170 °C and longer reaction times. Primary alkyl chlorides reacted with trichlorosilane (1) to give coupling products in good to excellent yields, but secondary alkyl chlorides reacted at a slower rate and gave lower yields of products. Coupling reactions with methyldichlorosilane instead of 1 proceeded at slower rates and gave lower yields of products.

Department of Chemistry, Graduate School, Yonsei University, Seoul 120-749, KoreaReceived May 8, 2002Friedel-Crafts alkylation reaction of an isomeric mixture of 1,2,3,4,5,6,7,8- (2) and 1,2,3,4,5,6,7,8-octahydrophenanthrene (2') with excess vinylchlorosilanes such as vinyl(methyl)dichlorosilane (1a) andvinyltrichlorosilane (1b) in the presence of aluminum chloride catalyst at 80

Publisher Summary This chapter discusses the reactivities of organo-silicon compounds for the Frieda–Crafts alkylation of aromatic compounds in the presence of aluminum chloride catalyst and the mechanism of the alkylation reactions. The reactivities of alkenylsilanes in the presence of a Lewis acid vary depending upon the nature of substituents on silicon. The substituent effect of vinylsilanes is similar to that of allylsilanes. The reactivity of vinylsilanes increased as the number of chlorine atom on the silicon increased, but decreased as the number of methyl groups increased. The rearrangement of alkylating agent under Friedel–Crafts reaction conditions and chloride exchange between aluminum chloride and alkyl chloride are well known. These indicate that the alkylation proceeds via the transitory existence of carbocations resulting from complexation between the alkylating agent and Lewis acid catalyst. The alkylation of mono-substituted benzenes gives an isomeric mixture of ortho, meta, and para-products. The ratio of isomeric products varies depending upon the electronic nature and steric bulk of the substituents on the benzene.

The new compound [C 6 H 5 Si(OCH 2 CH 2 ) 3 N]-Cr(CO) 3 has been prepared and characterized by elemental analysis, IR, 1 H NMR, and 13 C NMR spectroscopy, and X-ray diffraction. Crystallizes in the orthorhombic space group Pbca