Trimethylsilyl ethyne

It should be noted that 1,1-organoboration of Me3SiC=CMe with Et3B requires harsher conditions 100 °C and 24 h. Bis(trimethylsilyl)ethyne does not react with Et3B, but readily (20 °C) inserts into the 1-boraadamantane core giving rise to an equilibrium mixture containing c. 80% of 92 (Scheme 35). Treatment of this mixture with bis(trialkylstannyl)ethynes leads to the formation of distannane derivatives 93 (R = Me, Et) which seem to be more stable than 92 <2001JOM(620)51>. 

As mentioned above the 1,1-organoboration reaction is reversible, and exchange is slow on the NMR timescale. This statement is in agreement with the chemical behavior of equilibrated mixtures of products. Thus, treatment of silicon borahomoadamantane derivative 92 with bis(trimethylstannyl)ethyne leads to the tin-containing compound 93 and liberation of bis(trimethylsilyl)ethyne (Scheme 44). With pyridine, the equilibrium is moved toward 1-boraadamantane completely due to the complexation <2001JOM(620)51>. 

DihydroindolesA novel synthesis of fused dihydroindoles involves [2 + 2 + 2]cycloaddition of alkynes with the 2,3-double bond of N-alkynoylated pyrroles. The reaction of 1 with bis(trimethylsilyl)ethyne results in two diaster-... 

Annelated benzenesVollhardt s cocyclization of bis(trimethylsilyl)ethyne with... 

The reaction of bis(trimethylsilyl)ethyne (118) with a high boiling hydrosilane, HSiMe2C6Hi3-n, promoted by Karstedt s catalyst affords normal ris-addition product... 

Another reaction pathway of great synthetic usefulness is the addition of halogen across bis(trimethylsilyl)ethyne (i2)30 to isolate trans-l,2-dihalogeno-l,2-bis(tri-methylsilyl)ethenes 29 and 30. Further halogenation leads to symmetrical (31, 32) and nonsymmetrical (33) ethane compounds the pyrolysis of 31 yields 1,1,2-tri-chloro-2-(trimethylsilyl)ethene (34) (Scheme 5). 

Via an amidoalkylation of bis(trimethylsilyl)ethyne (12) with methyl 2-chloro-N-ethoxycarbonylglycinate (57) under the influence of aluminum chloride the corresponding N-(ethoxycarbonyl)-a,a-TMS-ethynyl-glycinate (55) is isolated which is converted by means of lithium-di-isopropylamide (LDA) into a carbanion that reacts with alkylhalide to the substituted glycinate 59. Finally, after alkaline hydrolysis the unprotected a-acetylenic-a-aminoacid (60) (e. g. R = Benzyl a-ethynyl-a-phenyl-alanine is then obtained (Scheme 7). 

At 60 °C, bicyclic titanacyclopentene complex 179 rearranges to 2-vinyl-substituted titanacyclobutene complex 180 in indeterminate yield (Equation 91) <1993CB1541>. This transformation proceeds by bis(trimethylsilyl)ethyne extrusion, rearrangement of the residual coordinated cyclopropene to vinylalkylidene, and [2+2] cycloaddition to reincorporate alkyne. 

The addition of alkoxycarbonylcarbene derived by catalysed decomposition of methyl diazoacetate to several simple, and in particular terminal, alkynes leads to low yields S7), but the reaction with 1 -trimethylsilylalkynes proceeds reasonably efficiently subsequent removal of the silyl-group either by base or fluoride ion provides a route to l-alkyl-3-cyclopropenecarboxylic acids. In the same way 1,2-bis-trimethylsilyl-ethyne can be converted to cyclopropene-3-carboxylic acid itself58 . The use of rhodium carboxylates instead of copper catalysts also generally leads to reasonable yields of cyclopropenes, even from terminal alkynes 59). 

The benzannulation reaction tolerates a range of alkyl and aryl allcynes, which may bear additional functionalities. The simultaneous presence of two bulky substituents directly attached to the C=C bond, as for example in bis(trimethylsilyl)ethyne, however, blocks the final electrocyclization and causes the reaction to stop at the vinyl ketene stage [44]. Neither very electron-rich nor very electron-poor allcynes can undergo benzannulation. Strongly electron-deficient allcynes such as hexafluorobut-2-yne cannot adequately compete with car-... 

Alkynyl(trimethyl)silanes smoothly couple with alkenyl halides at room temperature in the presence of a palladium catalyst and TASF (Eq. 5) [4]. The difference in reactivity between alkynylstannanes and -silanes were utilized in a palladium-catalyzed three component cross-coupling reaction. Thus, the palladium-catalyzed sequential reaction of tributylstannyl(trimethylsilyl)ethyne... 

The first synthesis of a diborirene of type 32 involved treatment of a 1,2-dichlorodiborane with bis(trimethylsilyl)-ethyne. An improved method analogous to Equation (18) employs magnesium reduction of (diboradichloromethyl-ene)alkenes (Equation 19) <1988ZNB801>. 

Anneiated benzenes.1 Vollhardt s cocyclization of bis(trimethylsilyl)ethyne with a.tu-diynes has been extended to several new partners. Thus a,trimethylsilyl)propyne and trimethylsilylalkynes. Examples are shown in equations (I) and (II). 

The substituted bis-Cp alkynyl-alkenyl (C5Me4R1)2Ti(G=CR2)(GH=GHR2) (Scheme 502) have been synthesized by reaction of the bis(trimethylsilyl)ethyne complex (G5Me4R1)2Ti(Me3SiC2SiMe3) with 1-alkynes the crystal structures have been determined by X-ray diffraction. Photolysis of these complexes involves dimerization processes with coupling of the two cr-ligands to give complexes with 1,4-disubstituted but-l-en-3-ynes.1287... 

The first isolated silacyclopropene (111) was prepared by thermolysis of hexamethyl-silacyclopropane in the presence of bis(trimethylsilyl)ethyne. The product proved to be thermally stable with a half-life of ca. 60 h at 70°C, (Scheme 40) (76JA6382,84JOM(272)i23>. 

Treatment of di-t-butyldichlorosilane with lithium in THF generated silanediyl (113), which was trapped with bis(trimethylsilyl)ethyne to give silacyclopropene (114) in excellent yield (Scheme 43)... 

Only rarely is proton loss observed from the intermediate cation derived from acylation of a terminal alkyne. In contrast, acylation of alkynylsilanes provides an excellent strategy for the synthesis of alkynyl ketones. " Here, it is apparent that elimination of the silyl substituent competes very effectively with capture of a nucleophile. Acylation of bis(trimethylsilyl)ethyne" provides a convenient route to terminal alkynic ketones, particularly since desilylation can be carried out using bases as weak as dilute aqueous borax, conditions mild enough to prevent the ready hydration of the triple bond (Scheme 25)." Silylated diynes are also excellent substrates for Friedel-Crafts acylation. ... 

The diazine substrate was prepared by reaction of the oxyanion of 2-bromophenol with 2-chloro-l,3-diazine followed by palladium(0)-mediated coupling with (trimethylsilyl)ethyne. 

AUcynylsilanes also are active such that dienynes are formed by the reaction of bis(trimethylsilyl)ethyne with alkynes. ... 

In the 2001 communication [32] the cyclobutadiene 13 made from the cyclo-propene 14 was contaminated with the bis(ketenimine) 16, which complicated positive identification of the tetrahedrane 12 formed when the when the (impure) 13 was photolyzed. The use of pure 13 [34], readily available from the dianion, starting with bis(trimethylsilyl)ethyne and CpCo(CO)2 or CpCo(H2C=CH2)2, facilitated the preparation and identification of the tetrahedrane [33],... 

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