Trimethylsilyl acetylene, with

Bromoalkynes also couple with vinylstannanes readily to result in enynes. Synthesis of protected enynals via cross-coupling of vinylstannanes with 1-bromoalkynes in the presence of a catalytic amount of Pd(II) has been reported (equation 143)252. Hiyama and coworkers extended the Stille methodology for sequential three-component coupling of trimethylstannyl(trimethylsilyl)acetylene with a vinyl iodide in the first step and cross-coupling of the intermediate trimethylsilylethyne with another alkenyl iodide in the presence of tris(diethylamino)sulphonium trimethyldifluorosilicate in the second step to generate a dienyne (equation 144)253. Both steps occur under palladium catalysis, in one-pot, to result in stereodefined l,5-dien-3-ynes. 

Internal RC=CR Symmetrically disubstituted acetylenes such as tolane PhC=CPh react with complex 1 by substitution of the bis(trimethylsilyl)acetylene with formation of the metallacydopentadiene 7 [2a,2d],... 

Phenyl 2-(trimethylsil>l)ethynyl sulfone, C6H5S02C=CSi(CH3)3 (1). Mol. wt. 238.38, m.p. 64-65°. Prepared by reaction of bis(trimethylsilyl)acetylene with C6H5S02C1-A1C13 in CH2C12 (65% yield).1... 

The treatment of (trimethylsilyl)acetylene with iodosylbenzene and boron trifluoride etherate does not give ethynyl(phenyl)iodonium tetrafluoroborate, but leads instead to (E)-1 -trimethylsilyl-2-ethoxyethynyl(phenyl)iodonium tetrafluoroborate (equation 26)79. 

A relatively new route to benzocyclobutenes, without the involvement of o-quinodimethanes, is the cobalt-catalyzed co-oligomerization of bis(trimethylsilyl)acetylene with 1,5-hexadiynes, (580) + (581) - (582) (Scheme 133). Despite its elegance, and the potential to modify the silyl groups, this method suffers from limitations in providing benzocyclobutenes with well-defined substitution patterns. In this... 

An elegant modification of this sort of intrmolecular cycloaddition strategy was reported by Funk and Vollhardt in 1980.81 Cooligomerization of bis(trimethylsilyl)acetylene with a substituted diyne under mild reaction conditions catalyzed by cyclopentadienylcobalt dicarbonyl gave a transfused tetracyclic adduct [Eq. (24)]. 

In a series of papers, Wong and co-workers detailed the preparation and use of 3,4-bis(trimethylsilyl)furans. Thus, after heating an equimolar mixture of 4-phenyloxazole and bis(trimethylsilyl)acetylene with 5 mol % of triethylamine in a sealed tube at 250°C for 2 days, an 80% yield of the desired furan 130 was obtained (Fig. 3.38). If the same reaction is performed in the presence of a catalytic amount of formic or trifluoroacetic acid instead of triethylamine, the analogous 2,4-bis-trimethylsilylfuran is obtained in good yield. Furan 130 itself reacts with alkynes in a tandem Diels-Alder retro-Diels-Alder sequence to provide other fiirans, e.g., 3,4-furandicarboxylic acid dimethyl ester 131. Friedel-Crafts acylations can also be performed using 130. In addition, 130 reacted with boron... 

Treatment of bis(trimethylsilyl)acetylene with tosyl chloride and a slight excess of anydrous Aluminum Chloride affords... 

Treatment of bis(trimethylsilyl)acetylene with tosyl chloride and a slight excess of anydrous Aluminum Chloride affords p-tolyl (trimethylsilyl)ethynyl sulfone, a precursor to the reactive Miehael acceptor ethynyl p-tolyl sulfone (eq 38). ... 

Monosubstitution of acetylene itself is not easy. Therefore, trimethylsilyl-acetylene (297)[ 202-206] is used as a protected acetylene. The coupling reaction of trimethylsilylacetylene (297) proceeds most efficiently in piperidine as a solvent[207]. After the coupling, the silyl group is removed by treatment with fluoride anion. Hexabromobenzene undergoes complete hexasubstitution with trimethylsilylacetylene to form hexaethynylbenzene (298) after desilylation in total yield of 28% for the six reactions[208,209]. The product was converted into tris(benzocyclobutadieno)benzene (299). Similarly, hexabutadiynylben-zene was prepared[210j. 

Potassium or lithium derivatives of ethyl acetate, dimethyl acetamide, acetonitrile, acetophenone, pinacolone and (trimethylsilyl)acetylene are known to undergo conjugate addition to 3-(t-butyldimethylsiloxy)-1 -cyclohexenyl t-butyl sulfone 328. The resulting a-sulfonyl carbanions 329 can be trapped stereospecifically by electrophiles such as water and methyl iodide417. When the nucleophile was an sp3-hybridized primary anion (Nu = CH2Y), the resulting product was mainly 330, while in the reaction with (trimethylsilyl)acetylide anion the main product was 331. 

Nitration of acetylenes with nitryl iodide followed by elimination of HI gives nitroacetylenes, but nitroacetylenes are too thermally unstable to be useful for organic synthesis.77 Recently, nitro-trimethylsilyl-acetylenes are prepared as stable nitroacetylenes by the reaction of bis(trimethylsily)acetylene with nitronium tetrafluoroborate (Eq. 2.39).78... 

Synthesis of Functionalized Enynes by Palladium/Copper-catalyzed Coupling Reactions of Acetylenes with (Z)-2,3-Dibromopropenoic Acid Ethyl Ester (Z)-2-Bromo-5-(trimethylsilyl)-2-penten-4-ynoic Acid Ethyl Ester. 

Reactions of salts of 1,2,3-triazole with electrophiles provide an easy access to 1,2,3-triazol-jV-yl derivatives although, usually mixtures of N-l and N-2 substituted triazoles are obtained that have to be separated (see Section 5.01.5). Another simple method for synthesis of such derivatives is addition of 1,2,3-triazole to carbon-carbon multiple bonds (Section 5.01.5). N-l Substituted 1,2,3-triazoles can be selectively prepared by 1,3-dipolar cycloaddition of acetylene or (trimethylsilyl)acetylene to alkyl or aryl azides (Section 5.01.9). 

Alkynyl-substituted sydnones 106 are prepared from the new trimethylsilylethynyl derivative 105. 4-Cuprio-3-phenylsydnone 104 <1996CHEC-II(4)165> reacts with l-bromo-2-trimethylsilyl acetylene to give product 105,... 

Dipolar cycloaddition reaction of trimethylstannylacetylene with nitrile oxides yielded 3-substituted 5-(trimethylstannyl)isoxazoles 221. Similar reactions of (trimethylstannyl)phenylacetylene, l-(trimethylstannyl)-l-hexyne, and bis (trimethylsilyl)acetylene give the corresponding 3,5-disubstituted 4-(trimethyl-stannyl)isoxazoles 222, almost regioselectively (379). The 1,3-dipolar cycloaddition reaction of bis(tributylstannyl)acetylene with acetonitrile oxide, followed by treatment with aqueous ammonia in ethanol in a sealed tube, gives 3-methyl-4-(tributylstannyl)isoxazole 223. The palladium catalyzed cross coupling reaction of... 

The zirconacyclopropene 1, which was prepared by treatment of Cp2ZrCl2 with magnesium metal in the presence of bis(trimethylsilyl)acetylene, reacted with one molecule of C02 under atmospheric pressure at room temperature to give the dimeric zirconacycle 2 in good yield (Scheme iy6>6a>6b Further insertion of C02 did not occur, although 2 has... 

Organometallic Chemistry of Titanocene and Zirconocene Complexes with Bis(trimethylsilyl)acetylene as the Basis for Applications in Organic Synthesis... 

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