Acetylene iodide

A similar quantitative treatment of sulphoxides as hydrogen bonding acceptors has been obtained by comparing the IR frequency shift AvOH of the C—I bond in an acetylenic iodide such as IC=CI (Avc j) due to formation of a C—T complex with phenol in various bases. This investigation suggests that sulphoxides belong to the same family as carbonyls, phosphine oxides, arsine oxides and their derivatives90. 

The utility of the creation of a y-lactone enolate through 1,4-addition of a carbanion and its interception by an electrophile has also been demonstrated in other classes of natural products, e.g., in the enantioselective synthesis of 10-oxa-l 1-methyl PGE2 analogues22. This synthesis starts with 1,4-addition of the sulfone-stabilized anion from 27 to ( + )-(S )-4-methyl-2-buteno-lide which has been prepared in three steps from (—)-(S)-l,2-epoxypropane. The intermediate enolate 28 is reacted with the acetylenic iodide to give the trisubstituted diastereomeric mixture of lactones 29, which is eventually converted into the pure compound 30, both reactions occurring with high diastereoselectivity. 

A more comprehensive study on the behavior of 5-acetylenic iodides in the presence of zinc was later reported21 and clearly revealed that when iodide 14 was treated with acid-washed zinc (pre-treated with Mel for activation and removal of traces of moisture) in a mixture of benzene and DMF, the acyclic organozinc iodide 21 and the cyclic vinyl iodide 22 were both produced. The amount of 22 increased significantly when the reaction mixture was sonicated rather than stirred or if a zinc-copper couple was used. The accumulation of compound 22 was consistent with its inability to be converted to an alkenyl organozinc species by reaction with metallic zinc under these conditions. However, no substantial cyclization of the open-chain organozinc 21 was observed. The formation of the five-membered ring compound 22 was attributed to a free-radical process... 

The carbometallation can be performed intramolecularly leading in this case to an unsaturated diorganonickel species of type 47 which undergoes a rapid reductive elimination furnishing polyfunctional cyclopentylidenes of type 48 (Scheme 9-41). The syn-addition is proven by using a phenyl-substituted acetylenic iodide such as 49 [78]. 

Jeffery, T. (1987) Palladium-catalyzed vinylation of acetylenic iodides under solid-liquid phase-transfer conditions. Synthesis, 70-1. 

The coupling of acetylenic iodides with copper sulfinates leads to the formation of uncommon acetylenic sulfones (Fig. 26). Sonication promotes this reaction, which can be made even easier by using a mixture of the sulfinic acid and commercial copper "carbonate" (a hydrated mixture of copper carbonate and hydroxide).i54 Successful results were also recorded in an extension using copper thiosulfonates and copper dimethyl phosphite. 

A general scheme for preparation of allenylcycloalkanols from cyclo-alkenones is shown in Scheme 14. Allenic and acetylenic iodides are obtained by iodinolysis of the acetylenic or allenic tin compounds (301) and (302).233... 

The rate of the reaction decreases with increasing number of substituents in the acetylenic halide, and it is higher with acetylenic bromides than with the corresponding chlorides. Methyl magnesium iodide gives equal amounts of 1,1- and 1,3--substitution products, whereas tert.-butylmagnesium bromide does not react. However, for some tert.-butyl substituted allenes there exists an attractive com-... 

Iodoallenes can also be prepared in reasonable yields by treatment of secondary acetylenic alcohols with triphenylphosphite-methyl iodide, using DMF as a solvent. One of the -OPh groups is probably first replaced by the propargyloxy group. This intermediate subsequently undergoes attack by iodide on the terminal acetylenic carbon atom, affording the iodoallene in a 1,3-substitution ... 

Alkynes undergo stoichiometric oxidative reactions with Pd(II). A useful reaction is oxidative carboiiyiation. Two types of the oxidative carbonyla-tion of alkynes are known. The first is a synthesis of the alkynic carbox-ylates 524 by oxidative carbonylation of terminal alkynes using PdCN and CuCh in the presence of a base[469], Dropwise addition of alkynes is recommended as a preparative-scale procedure of this reation in order to minimize the oxidative dimerization of alkynes as a competitive reaction[470]. Also efficient carbonylation of terminal alkynes using PdCU, CuCI and LiCi under CO-O2 (1 I) was reported[471]. The reaction has been applied to the synthesis of the carbapenem intermediate 525[472], The steroidal acetylenic ester 526 formed by this reaction undergoes the hydroarylalion of the triple bond (see Chapter 4, Section 1) with aryl iodide and formic acid to give the lactone 527(473],... 

Assume that you need to prepare 4 methyl 2 pentyne and discover that the only alkynes on hand are acetylene and propyne You also have available methyl iodide isopropyl bromide and 1 1 dichloro 3 methylbutane Which of these compounds would you choose in order to perform your synthesis and how would you carry it out" ... 

It looks as though all that is needed is to prepare the acetylenic anion then alkylate it with methyl iodide (Section 9 6) There is a complication however The carbonyl group m the starting alkyne will neither tolerate the strongly basic conditions required for anion formation nor survive m a solution containing carbanions Acetyhde ions add to carbonyl... 

Titanium tetraiodide can be prepared by direct combination of the elements at 150—200°C it can be made by reaction of gaseous hydrogen iodide with a solution of titanium tetrachloride in a suitable solvent and it can be purified by vacuum sublimation at 200°C. In the van Arkel method for the preparation of pure titanium metal, the sublimed tetraiodide is decomposed on a tungsten or titanium filament held at ca 1300°C (152). There are frequent hterature references to its use as a catalyst, eg, for the production of ethylene glycol from acetylene (153). 

Acetyl cyclohexane sulfonyl peroxide, 7 Acetyl Iodide, 7 Acetyl thiourea, 8 Acetylaminofluorene, 7 Acetylene, 7... 

Perfluoroalkylation of perfluoroalkylethylenes and addition of perfluoroalkyl iodides to olefins or acetylenes are catalyzed by copper metal [238, 239] Similar copper-catalyzed addition of iododifluoroacetates to olefins has been observed [241]... 

The reaction of these acetylenic copper compounds with perfluorovinyl iodides stereospecifically gives the perfluoroeneynes [147, 755] (equations 172 and 173). 

Examples of perfluoroalkyl iodide addition to the triple bond include free radical addition of perfluoropropyl iodide to 1 -heptyne [28] (equation 21), thermal and free radical-initiated addition of lodoperfluoroalkanesulfonyl fluorides to acetylene [29] (equation 22), thermal addition of perfluoropropyl iodide to hexa-fluoro 2 butyne [30] (equation 23), and palladium-catalyzed addition of per-fluorobutyl iodide to phenylacetylene [31] (equation 24) The E isomers predominate in these reactions Photochemical addition of tnfluoromethyl iodide to vinylacetylene gives predominantly the 1 4 adduct by addition to the double bond [32] Platinum catalyzed addition of perfluorooctyl iodide to l-hexyne in the presence of potassium carbonate, carbon monoxide, and ethanol gives ethyl () per fluorooctyl-a-butylpropenoate [JJ] (equation 25)... 

Electrochemical addition of perfluorobutyl iodide to 2-methyl-3-butyn-2-ol followed by basic dehydroiodmation and thermal cleavage gives perfluorobutyl-acetylene in an overall yield of 83% [34] (equation 26)... 

In the presence of dicyclohexyl-18-crown-6 ether, potassium fluoride converts fluonnated vinylic iodides to acetylenes [2] (equation 2)... 

The treatment of LiN(SiMc3)2 with aryl tellurenyl iodides gives stable Ai,iV -bis(trimethylsilyl)tellurenamides that react with acetylenes to give acetylenyl tellurides (Eq. 2.4). 

The 3,5-bis(trifluoromethyl)pyrazolate analog [Ir(cod)(/x-3,5-(CF3)2pz)]2 does not enter into oxidative addition with iodine, methyl iodide, or acetylenes. The mixture of pyrazolate and 3,5-bis(trifluoromethyl)pyrazolate gives [(rj -codllrf/x-pz)(/L-3,5-(CF3)2pz)Ir(rj -cod)], which reacts with bis(trifluoromethyl)acetylene in a peculiar manner [83JCS(CC)580], producing 145, where 3,5-bis(trifluoromethyl) pyrazolate is replaced by the ethylene bridge and the rj -coordination mode of one of the cod ligands is converted into the rj -allylic mode. 

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