53366-55-5

Usage

Synthesis Reference(s)

The Journal of Organic Chemistry, 49, p. 4244, 1984 DOI: 10.1021/jo00196a026

Upstream product

• 14093-35-7 1,10‐dichlorodec‐5‐yne 
• 42049-41-2 1-iodo-5-decyne 
• 35843-78-8 1-bromo-5-decyne 

Relevant academic research and scientific papers

Catalytic reduction and intramolecular cyclization of haloalkynes in the presence of nickel(I) salen electrogenerated at carbon cathodes in dimethylformamide

Pentylidenecyclopentane can be conveniently prepared in up to 86% yield via the catalytic reduction of 1-iodo- or 1-bromo-5-decyne by [[2,2′-[1,2- ethanediylbis(nitrilomethylidyne)]bis[phenolato]]-N,N′,O,O′] -nickelate(I) electrogenerated at a carbon cathode in dimethylformamide containing tetramethylamnionium tetrafluoroborate. This electrosynthesis can be accomplished at potentials for which the haloalkynes are electroinactive, and it can be completed within 30 min at room temperature. Attempts to synthesize pentylidenecyclobutane and pentylidenecyclohexane from 1-halo-4-nonynes and 11-halo-5-undecynes, respectively, under similar conditions afford the carbocycles in very low yields (2% and 6%, respectively), Other products derived from the various haloalkynes are dimers, alkynes, and 1-alkenynes. Dimers (alkadiynes) arising From 1-halo-4-nonynes and 11-halo-5-undecynes are formed in yields ranging from 80% to 89%, whereas icosa-5, 15-diyne (the dimer obtained from a 1-halo-5-decyne) is found in significantly lower yield (≤ 13%). Alkynes and 1-alkenynes are produced in yields of 3-10% and 2-3%, respectively. A mechanistic scheme, involving alkyn-1-yl radicals arising from niekel(I) salon catalyzed cleavage of the carbon-halogen bond of each haloalkyne, is proposed to account for the formation of all products.

Cyclizations during the Grignard Reactions of ω-Bromoalkynes

The Grignard reactions of a number of ω-bromoalkynes have been shown to undergo regioselective cyclizations in certain instances to give the smaller possible carbocycle. These cyclizations are shown to result from two competing processes, whose relative efficiencies depend upon the chain length and the remote substitutent on the acetylene. These are interpreted as a radical cyclization which occurs only during the time the Grignard is being formed from the bromide and an organometallic reaction which slowly transforms the Grignard reagent into its cyclic isomer. The mechanistic details of these transformations are discussed.

Reactions of some alkynyl halides with samarium(II) iodide

Certain alkynyl halides (6-halo-1-ynes) react with samarium(II) iodide (SmI2) to give cyclized products (methylenecyclopentanes) in good yield. We have found some interesting evidence for the presence of radical and unstable organosamarium intermediates in these reductive cyclizations. Methyl 7-halohept-2-ynoates are not, however, good substrates for this cyclization methodology.

PREPARATION AND FACILE CYCLIZATION OF 5-ALKYN-1-YLLITHIUMS

Primary 5-hexyn-1-yllithiums, which may be generated in virtually quantitative yield by low-temperature lithium-iodine interchange, undergo regiospecific 5-exo-dig cyclization via stereoselectively syn-addition of CH2Li to the alkyne moiety to give vinyllithiums that may be trapped with any of a variety of electrophiles to deliver functionalized cyclopentylidene-containing products.

Electrochemical Reduction and Intramolecular Cyclization of 1-Iodo-5-decyne and 1-Bromo-5-decyne at Vitreous Carbon Cathodes in Dimethylformamide

In dimethylformamide containing tetramethylammonium perchlorate, cyclic voltammograms for reduction of 1-iodo-5-decyne and 1-bromo-5-decyne at a vitreous carbon electrode each consist of a single irreversible wave due to two-electron scission of the carbon-halogen bond.Preparative-scale electrolyses of 1-iodo-5-decyne yield pentylidenecyclopentane, 5-decyne, 1-decen-5-yne, and a small amount of 5-decyn-1-ol, whereas reduction of 1-bromo-5-decyne affords mainly 5-decyne and 1-decen-5-yne along with a modest quantity of pentylidenecyclopentane.Differences in product distributions correlate with the extent to which the 5-decyn-1-yl radical persists as a transient species.Pentylidenecyclopentane arises via intramolecular cyclization of the 5-decyn-1-yl radical followed by hydrogen atom abstraction, 5-decyne is formed via protonation of the 5-decyn-1-yl carbanion by either water or the tetramethylammonium cation, and 1-decen-5-yne and 5-decyn-1-ol are obtained, respectively, via E2 and SN2 reactions between unreduced starting material and hydroxide ion (generated by deprotonation of water).In the presence of a proton donor (diethyl malonate or hexafluoroisopropyl alcohol), the quantities of pentylidenecyclopentane and 5-decyne rise noticeably and the yield of 1-decen-5-yne falls dramatically.

Cyclizations of ω-Alkynyl Halides by Cr(II) Reduction

Reduction of halides of the types RCC(CH2)nX with Cr(II) in aqueous DMF containing ethylenediamine proceeds by way of the intermediate radicals which cyclize regioselectively in the n=4 and n=5 cases to give substituted methylenecycloalkanes.Experimental conditions which favor longer lifetimes for the intermediate radicals (low concentrations, slow addition times, and an inverse-addition mode) result in increased cyclization.The iodides curiously give more cyclic product than the corresponding bromides.These results are discussed.

Electrochemical Reduction of 1-Iodo-5-decyne and 1-Bromo-5-decyne at Mercury Cathodes in Dimethylformamide

Pulse polarograms for 1-iodo-5-decyne in dimethylformamide containing tetramethylammonium perchlorate exhibit two waves.At potentials corresponding to the first wave, electrolysis of 1-iodo-5-decyne at mercury results in 5-decynyl radicals that (i) adsorb onto and interact with the mercury electrode to give 5-decynylmercury radicals which disproportionate into di-5-decynylmercury or (ii) cyclize and then accept a hydrogen atom to yield pentylidenecyclopentane.At potentials on the second wave, reduction of 1-iodo-5-decyne is largely a two-electron process leading to the 5-decynyl carbanion which is protonated by water in the solvent-supporting electrolyte to yield 5-decyne and hydroxide ion; hydroxide ion then attacks unreduced starting material to give 1-decen-5-yne and 5-decyn-1-ol.In the presence of excess proton donor (diethyl malonate), neither 1-decen-5-yne nor 5-decyn-1-ol is obtained, but diethyl 5-decynylmalonate is produced, the quantity of 5-decyne is increased, and the coulometric n value is raised.Pulse polarograms for 1-bromo-5-decyne show a single wave.For reduction of 1-bromo-5-decyne, the yields of 5-decyne and 1-decen-5-yne are comparable to those derived from 1-iodo-5-decyne; some di-5-decynylmercury is produced, but no pentylidenecyclopentane is formed.