Trimethylsilyl-1,3-butadiyne

In a semimicro synthesis selenophene is prepared from bis(trimethylsilyl)-1,3-butadiyn and NaHSe generated in situ from Se and NaBH4 in aqueous dimethylformamide.52 Other ring cyclization reactions have been performed... 

Nucleophilic additions of alcohols, amines, thiols, and selenols to Group 8 butatrienylidene intermediates [M]=C=C=C=CR2 have also been used in the preparation of stable heteroatom-conjugated allenylidene complexes. Thus, activation of trimethylsilyl-1,3-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)... 

The hydrosilylation of 1,4-bis(trimethylsilyl)-1,3-butadiyne catalyzed by H2PtCl6, RhCl(PPh3)3 or Pt(PPh3)3 gives an enyne (22) and/or an allene (23) 22 arises from the mono-hydrosilylation and 23 from dowb/e-hydrosilylation191 (equation 54). 

Palladium-catalyzed bis-silylation of l,4-bis(trimethylsilyl)butadiyne affords 1,2- and 1,4-addition products with varying ratios, depending on the disilanes and palladium catalysts used (Equation (28)).98... 

C, pot temperature 125°C) prior to collection of the product. (Z)-2-Bromo-5-(trimethylsilyl)-2-penten-4-ynoic acid ethyl ester is collected (bp 105-108°C, 0.9 mm, pot temperature < 125°C) as a pale yellow oil (10.95-12.85 g, 48-56%) and is shown by capillary GC to be 87-94% pure (contaminants include bis(trimethylsilyl)butadiyne, < 2% and (E)-2-[(trimethylsilyl)ethynyl]-5-(trimethylsilyl)-2-penten-4-ynoic acid ethyl ester, 6-11% Notes 11-13). 

Phenyl azide reacts slowly with bis(trimethylsilyl)butadiyne at elevated temperature to give 1,2,3-triazole (718) as the only product. Similar reaction of 4-nitrophenyl azide and bis(trimethyl-... 

Scheme3.7 Formation of a silyl-substituted butatrienylidene iron complex by reaction of [FeCI(Cp )(dppe)j with trimethylsilyl butadiyne.

Bis(trimethylsilyl)butadiyne forms, on reaction with dicobalt octa-... 

Cyclopentadienylnickel carbonyl dimer is also known to react with acetylenes to form bridged complexes. With bis(trimethylsilyl)acetylene and with l,4-bis(trimethylsilyl)butadiyne it reacts to give organosilyl acetylene complexes 63) [Eqs. (47) and (48)]. The silylated butadiyne... 

The radical anion of /3-trimethylsilylstyrene also undergoes dimerization but coupling takes place at the carbons a to silicon 33). The kinetics of the alkyne dimerization, followed by ESR, showed the reaction to be second order in radical anion 43). With Li+, Na+, K+, or Rb+ as the counterions, the rate increases in the order Si < C < Ge 45). Consistent with the increased stability of the trimethylsilyl-substituted radical anion, the radical anion of 1,4-bis(trimethylsilyl)butadiyne, produced by reduction with Li, Na, K, Rb, or Cs in THF is stable at room temperature even on exposure to air, whereas the carbon analog, 1,4-di-r-butyl-1,3-butadiyne radical anion, dimerizes by second-order kinetics at -40° (42). The enhanced stability of the trimethylsilylalkynyl radical anions has been attributed to p-drr interactions (42). 

The acetone is removed by evaporation with a rotary evaporator, and the residue is dissolved in petroleum ether (bp 30-40°C, 150 mL) (Note 9) and shaken in a separatory funnel with 3 M aqueous hydrochloric acid (150 mL). The phases are separated and the aqueous phase is washed with petroleum ether (bp 30-40°C, 3 x 150 mL). The combined organic layers are washed with saturated aqueous sodium chloride (50 mL), dried (NagSO ), and evaporated to dryness with a rotary evaporator. The solid residue is dissolved in hot methanol (400 mL) to which has been added 3 M aqueous hydrochloric acid (4 mL). The solution may be filtered at "this stage if it is necessary to remove colored Insoluble Impurities. Water is then added dropwise until recrystallized material is permanently present. The solution is allowed to cool, finally in ice, and crystalline bis(trimethylsilyl)butadiyne (BTMSBD) is collected. The material is washed with a small portion of ice-cold methanol-water (50 50 v/v 50 mL), and dried in the air to give bis(trimethylsilyl)-butadiyne (31-35 g, 68-76%), mp 111-112°C (lit.2,3 107-108°C) (Note 10). A further 3-5 g (6-10%) of the product is obtained from the mother liquors (Notes 11 and 12). ... 

The reaction" of CpCo(CO)2 with MesSi—C=C — SiMes at 137 °C provides a simple thermal example of such a cleavage. The reaction also involves dimerization of the substrate, and it seems likely that it may proceed via bis (trimethylsilyl)butadiyne. 

A dinuclear Pt(0)-cod complex with a vr-coordinated bis(trimethylsilyl)butadiyne ligand 808 undergoes exchange of the ligand with a chelating aminophosphine to form 809 (Scheme Activation of the Si-C bonds is... 

Ladika and Stang have demonstrated that bis(trimethylsilyl)butadiyne (212) can be converted, via l-(butadiynyl)vinyl trifluoromethanesulphonates, e.g. (213), into unsymmetrical conjugated triynes, e.g. (214). ... 

Similar to the reaction of zirconacyclopentadiene with main group dihalides EX2, the Cp2Ti unit in titanacyclopentadiene could also be replaced directly by main group elements to give five-membered heteroaromatic cycles. For example, titanacyclopentadiene 85, which was prepared by the homocoupling of 1,4-bis(trimethylsilyl)butadiyne, reacted with sulfur monochloride to give thiophene derivative 86 in a moderate yield, as shown in Scheme 11.33 [34]. 

Selenophens.— The preparation of selenophen by the action of sodium hydrogen selenide on bis(trimethylsilyl)butadiyne, Me3SiC=C—C=CSiMe3, has been described. The reaction of dimethyl acetylenedicarboxylate with the potassium salt PhC=CSe yields the ester (270), together with a little of the diselenole (271). Treatment of dibenzylideneacetone with selenium tetrabromide gives compound (272), which is converted into the benzoselenophen (273 R = COCH=CHPh) in the presence of pyridine.The ester (273 R = C02Et) has been obtained by cyclization of ethyl o-methylselenocinnamate (274) by means of bromine and pyridine. 

Computational studies of the thermal reactions of silene (Me3Si)2Si C(OSiMe3)(t-Bu) with silyl-substituted acetylenes, bis(trimethylsilyl)butadiyne, t-butyldimethylsilylacet-ylene, and bis(trimethylsilyl)acetylene report substituent effects in the reactivity of the silene. A regioselective migration of a sulfonyl group for the synthesis of functionalized pyrroles can be controlled with high selectivity for the formation of both a- and / -(arylsulfonyl)methyl pyrroles. 

Naka A, Ishikawa M (2002) Reactions of silenes produced thermally from pivaloyl- and adamantoyltris(trimethylsilyl)silane with bis(trimethylsilyl)butadiyne. Chem Lett 364... 

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],... 

---