Acetylene derivs propargyl

Acetylene is condensed with carbonyl compounds to give a wide variety of products, some of which are the substrates for the preparation of families of derivatives. The most commercially significant reaction is the condensation of acetylene with formaldehyde. The reaction does not proceed well with base catalysis which works well with other carbonyl compounds and it was discovered by Reppe (33) that acetylene under pressure (304 kPa (3 atm), or above) reacts smoothly with formaldehyde at 100°C in the presence of a copper acetyUde complex catalyst. The reaction can be controlled to give either propargyl alcohol or butynediol (see Acetylene-DERIVED chemicals). 2-Butyne-l,4-diol, its hydroxyethyl ethers, and propargyl alcohol are used as corrosion inhibitors. 2,3-Dibromo-2-butene-l,4-diol is used as a flame retardant in polyurethane and other polymer systems (see Bromine compounds Elame retardants). 

Titanated vinylallenes generated from the coupling of acetylenes and propargyl carbonates [38] undergo facile, unidirectional electrocyclization to give cyclobutene derivatives under extremely mild reaction conditions as shown in Eq. 9.17 [39]. 

Omite [2312-35-8] -propargyl alcohol m [ACETYLENE-DERIVED CHEMICALS] (Vol 1)... 

In the following steps (eq 7), we observed two HCl-catalyzed processes an acetylenic-allene rearrangement (to 10) and an allenic-acetylene rearrangement (to 11). While both 10 and 11 were easily identified by their characteristic NMR signals and could be distilled as a mixture without decomposition, only the final acetylene derivative (11) could be isolated in pure form after fractional distillation. Propargyl bromide reacted similarly with the three-coordinate phosphine, but in this case all of the chemical transformations occurred very rapidly and only the final acetylene phosphoranimine (11) could be isolated. 

Some multicomponent syntheses of trisubstituted oxazoles were described. a-Isocyano-a-alkyl(aryl)acetamides, as 131 <05S161>, was demonstrated to be a useful starting material for a three-component reaction involving isoquinoline 129 <05SL532>. A four-component synthesis was also published starting from an aldehyde, a silylamide, an acyl chloride and a terminal acetylene derivative. The overall process is a modification of a four-component synthesis of a propargylic amide 134 which can be eventually isolated <05T 11317>. 

The alkyne-Co2(CO)6 complexes 1 are the binuclear cluster complexes of the acetylenic derivatives with the hexacarbonyldicobalt moiety. These complexes can be readily prepared by treatment of alkynes with commercially available octacarbonyldicobalt [Co2(CO)g] and can regenerate the parent triple bond functionality under some mild oxidation conditions. Two synthetically very useful reactions have so far been developed by taking advantage of the characteristic properties of the alkyne-Co2(CO)6 complexes 1 one is so-called Nicholas reaction" and the other is so-called Pauson-Khand reaction (Scheme 1). The alkyne-Co2(CO)6 complexes 1 possessing a hydroxyl group or its equivalent at carbon p- to alkyne moiety (propargyl alcohol derivatives) could easily... 

Hydrostannation. Enestannanes from acetylene derivs. An equimolar amount of NaBH4 in ethanol added dropwise to tri-n-butyl-tin chloride in abs. ethanol, stirred 10 min. at 25°, propargyl 2-tetrahydropyranyl ether added, and refluxed 3.5 hrs. -> trans-3-tri-rt-butylstannyl-2 -propenyl 2-tetrahydropyranyl ether. 

ButyllithiumI triethylenediamine One-pot 1,3-disubstitution of acetylene derivs. via propargylic dicarbanions 805. CH3-C=CH... 

MEYER - SCHUSTER Propargyl alcohol rearrangement Add catalyzed rearrangement of acetylenic alcohols into o, -unsaturated carbonyl derivatives... 

This catalyst was successfully applied to the Diels-Alder reaction of propargyl aldehydes as dienophUes [12] (Scheme 1.21, Table 1.8). Though 2-hutyn-l-al and 2-oc-tyn-l-al are unreactive dienophUes, silyl- and stannyl-suhstituted a,/ -acetylenic aldehydes react with cydopentadiene readily in the presence of 20 mol% of the catalyst at low temperature to give hicyclo[2.2.1]heptadiene derivatives in high optical purity these derivatives are synthetically useful chiral building blocks. 

Using propargyl alcohols and propargylamine derivatives as acetylenic compounds, the silylformylation reaction affords, in the presence of a base, a-silylmethylene-P-lactones, I, and P-lactams, II, respectively (Scheme 3) [13]. 

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