Copper-zinc reagents, reaction

Propargylic copper/zinc reagents Reaction of alkynylcoppcrs with iodomcthyl-zinc iodide (Simmons-Smith reagent) provides propargylic copper/zinc reagents, which react with aldehydes or ketones to form homopropargylic alcohols in 80-95% yield. 

Substitution Reactions with Copper-Zinc Reagents... 

Scheme 2.38. Reactions between copper-zinc reagents and cationic metal complexes.

Scheme 2.41. Substitution reactions with copper-zinc reagents by addition-elimination mecha-...

Scheme 2.44. Addition-elimination reactions involving copper-zinc reagents.

Scheme 8.3. Conjugate Addition and Alkylation Reactions of Mixed Copper-Zinc Reagents...

SCHEME 87. Addition-elimination reactions of copper-zinc reagents with various Michael acceptors bearing a leaving group in h -position... 

SCHEME 93. Addition reactions of zinc and copper-zinc reagents to carbonyl compounds... 

Copper-zinc reagents, in asymmetric addition reactions, 9, 110 Core-functionalized dendrimers as catalyst hosts, 12, 803 as organometallic hosts, 12, 800 Core-valence ionization correlations, and photoelectron spectroscopy, 1, 394... 

Copper catalysed substitution reactions require high reaction temperatures and polar solvents like NMP.9 With activated alkenyl iodides bearing electron-withdrawing groups, copper-zinc reagents react readily leading to addition-elimination products.10-11 This method can be used to prepare a range of polyfunctional unsaturated molecules (Scheme 10.3).10-12... 

While the reaction of acid chlorides with organoz-inc halide compounds is relatively inefficient, the reaction with the corresponding copper-zinc reagents or the catalysis with Pd salts represents a smooth route for the preparation of ketones in very good yields (equation 58). 

C. (E)-2-(4-Hydroxy-6-phenyl-5-hexenyl)-1H-lsolndole-1,3(2H)-dione 4. The THF solution of the copper-zinc reagent is cooled to -78°C and 19.9 mL (162 mmol) of boron trifluoride etherate (Note 13) is added dropwise. The reaction mixture is warmed to -30 C and stirred for 30 min, then cooled to -60°C. (E)-Cinnamaldehyde (5.71 g, 43.2 mmol) is added slowly via a syringe. The reaction mixture is allowed to stir at -30 C for 14 hr (Note 14) and for 30 min at 0°C. After this time, conversion is complete as Indicated by GLC analysis and the reaction mixture is poured into an Erlenmeyer flask containing 500 mL of ethyl acetate, 100 mL of a saturated aqueous... 

Another type of o-aminobenzyl synthon is based on o-(bis-trimethylsilylaminobenzyl)copper-zinc reagents <89TL4795>. These are prepared from the corresponding benzylic bromides by reaction with zinc, followed by addition of cuprous cyanide. These reagents react with acid chlorides to give 2-substituted indoles. Since the reactions proceed by C-acylation rather than iV-acylation, the conditions required for cyclization are mild and typically the C-acylated intermediates are not isolated. 

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