Carbocupration of alkynes

The Conia-ene reaction is a thermal cyclization of an alkyl ketone with an alkyne to give the corresponding a-vinylated ketone.98 The catalytic version of this reaction has been reported to generalize the process to more functionalized substrates.99 The intramolecular carbocupration of alkyne 94 has been investigated under basic conditions in the presence of a catalytic amount of copper iodide (Scheme 28).100 The cyclic product 95 is obtained in high yield. 

Carbocupration of alkynes by zirconacyclopentane derivatives can be performed according to the same procedure. Thus, the zirconocyclopentane 135, obtained by treatment of Bu2ZrCp2 with 1,6-heptadiene, reacts at room temperature with phe-nylacetylene to afford the adduct 136 through a carbocupration-reductive elimination mechanism. Cross-coupling followed by intramolecular carbocupration takes place in the case of the reaction with 1-bromohexyne, producing 137 (Scheme 2.66) [143]. 

The carbocupration of alkynes occurs in a cis fashion to afford the synthetically useful cis alkenyl products. Recently, copper-mediated introduction of heteroatoms such as stannyl and silyl groups has become frequently used in place of introduction of carbon units as an efficient strategy to build important precursors in syn-... 

In a similar manner, alkynes can undergo sequential carbometallation reactions, previously illustrated in equation (32).136 It is possible to combine carbocupration of alkynes with the use of a Michael acceptor as electrophile when that electrophile is a vinylphosphonium salt, carbocupration can be coupled to Wittig alkenation to result in a stereospecific synthesis of dienes via a one-pot, four-component, four carbon-carbon bond-forming reaction sequence.302... 

CARBAMIC ACID, (2-METHYL-2-BUTENYL)-, METHYL ESTER, 65, 159 Carbamic add, methyl ester, 65,159 Carboalumination of alkynes. 66, 64 Carbocupration of alkynes, 66, 65... 

A Prelude Preparation of Haloalkenes and Alkenylboronic Acid Derivatives, Important Building Blocks for Palladium-Mediated C,C Couplings Carbocupration of Alkynes... 

The carbocupration of alkynes, that is, the addition to a non-activated C-C triple bond, is another classical reaction of organocopper compounds. Due to the high regioselectivity and m-stereoselectivity usually observed in... 

Carbocupration of alkynes using trimeethylsilylmethylcopper reagents followed by the reaction with allyl bromide provides highly substituted allylsilanes useful for further synthetic transformations (Scheme 3-56). ... 

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