Trimethylsilyl-l,3-butadiyne

The reaction of l,4-bis(trimethylsilyl)-l,3-butadiyne (174) with disilanes, followed by treatment with methylmagnesium bromide, produces i,l,4,4-tetra(-trimethylsilyl)-l,2,3-butatriene (175) as a major product[96]. The reaction of octaethyltetrasilylane (176) with DMAD proceeds by ring insertion to give the six-membered ring compounds 177 and 178[97], The l-sila-4-stannacyclohexa-2,5-diene 181 was obtained by a two-step reaction of two alkynes with the disilanylstannane 179 via the l-sila-2-stannacyclobutane 180[98],... 

Similar to the reaction of zirconacyclopropene 1, titanacyclopropene 14 reacted with C02 to give titanacycle 15 (Scheme 5) I0,i0a-i0c j-[owever5 the reaction of Cp TiC /Mg with l,4-bis(trimethylsilyl)-l,3-butadiyne did not afford a titanacyclocumulene species, but yielded titanacyclopropene instead 16, which on reaction with C02 gave the titanacycle complex 17.7 In the case of the titanium half-metallocene complex 18, the five-membered titanacyclocumulene 19 was obtained but the insertion of C02 took place only at one of the two Ti-carbon bonds, leading to the formation of 20 (Scheme 5),11 which is in contrast with what was observed in the case of the Zr analog 3. The... 

Nucleophilic additions of alcohols, amines, thiols, and selenols to Group 8 buta-trienylidene intermediates [M]=C=C=C=CR2 have also been used in the preparation of stable heteroatom-conjugated allenylidene complexes. Thus, activation of trimethylsilyl-l,3-butadiyne HC=C-C=CSiMe3 by the iron(II) complex [FeClCp (dppe)], in methanol and in the presence of NaBPh4, resulted in the high-yield formation of the methoxy-allenylidene [FeCp =C=C=C(OMe)Me ... 

Benzeneseleninic anhydride-Cyanotri-methylsilane, 28 N-Benzyl-N-methoxymethyl-N-(trimethylsilyl)methylamine, 31 0,N-Bis(trimethylsilyl)acetamide, 34 Bis(trimethylsilyl)acetylene, 97, 309 1,4-Bis(trimethylsilyl)-l, 3-butadiyne, 179... 

GaCl3 mediates the reaction of l,4-bis(trimethylsilyl)-l,3-butadiyne with aromatic hydrocarbons at —90 to —100°G yielding 2-aryl-l-buten-3-ynes 112 and 113. The reaction exhibits a high tendency to alkenylate the 0-position of alkyl... 

Tellurophene1 A 1 /, three-necked flask is fitted with a reflux condenser, a stirrer, an addition funnel, and a nitrogen inlet tube. 4.0 g (31 mmol) of tellurium, 28 g(200 mmol) of 85% sodium formaldehyde sulfoxylate, 17 g (425 mmol) of sodium hydroxide, and 150 ml of water are placed in the flask which is then purged with pure nitrogen. The stirred mixture is heated under reflux for 15 min and cooled to 20°. 8.2 g (42 mmol) of 1,4-bis[trimethylsilyl]-l,3-butadiyne dissolved in 100 m/ of ethanol are slowly added dropwise to the stirred sodium telluride solution, the mixture is heated under reflux for 15 min, then stirred at 20° for 3 h, extracted with diethyl ether, and the extract is dried with anhydrous sodium sulfate. The extract is filtered and 10 ml (200 mmol) of bromine are added dropwise to the filtrate until the bromine color persists. The solution is concentrated on a water bath at 40° under aspirator vacuum to a volume of 50 ml and the red precipitate of tellurophene. dibromide is collected yield 8.9 g (84%) m.p. 120° (dec.). 

The hydrosilation of l,4-bis(trimethylsilyl)-l,3-butadiyne gives either enynes as the product of monohydrosi-lation or allenes as deriving from di-hydrosilation (equation 15). ... 

A synthesis which is more convenient for the small-scale preparation of tellurophene employs sodium telluride, formed by the reduction of tellurium with sodium formalde-hydesulfoxylate in aqueous sodium hydroxide, and 1,4-bis[trimethylsilyl]-l, 3-butadiyne ... 

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