Allylic halides coupling

Dienes. Active barium prepared by treating Balj with couples allylic halides in... 

Allylic amines are coupled to halides giving either allylic amines or enamines depending on the reaction condition. Reaction of steroidal dienyl triflate with Boc-diprotected allylamine affords allylamine. Use of AcOK as a base is crucial for the clean coupling[102]. The tert-allylic amine 123 reacts with an aryl halide to give the enamine 125 in DMF and allylic amine 124 in nonpolar solvents[103]. 

Perfluoroalkylzinc iodides, prepared in situ from iodides and ultrasonically dispersed Zn, are coupled with allylic halides via an allylic rearrangement[271]. The Pd-catalyzed homocoupling of allylic acetate in the presence of Zn to give a mixture of regioisomers 416 and 417 may proceed via in situ formation of allylzinc species[272,273]. 

Lithiation at C2 can also be the starting point for 2-arylatioii or vinylation. The lithiated indoles can be converted to stannanes or zinc reagents which can undergo Pd-catalysed coupling with aryl, vinyl, benzyl and allyl halides or sulfonates. The mechanism of the coupling reaction involves formation of a disubstituted palladium intermediate by a combination of ligand exchange and oxidative addition. Phosphine catalysts and salts are often important reaction components. 

One of the most gentle methods for the generation of reactive allylmetallic reagents was introduced in 1977 by Hiyama and Nozaki1,2,3,33. By the action of two equivalents of chromi-um(II) chloride on allylic halides in tetrahydrofuran at 0°C in the presence of a carbonyl compound, reductive coupling with the formation of a homoallylic alcohol takes place. 

Alkenylboranes (R2C=CHBZ2 Z — various groups) couple in high yields with vinylic, alkynyl, aryl, benzylic, and allylic halides in the presence of tetra-kis(triphenylphosphine)palladium, Pd(PPh3)4, and a base to give R C CHR. 9-Alkyl-9-BBN compounds (p. 1013) also couple with vinylic and aryl halides " as well as with a-halo ketones, nitriles, and esters.Aryl halides couple with ArB(IR2 ) species with a palladium catalyst. ... 

In another method for the coupling of two different allylic groups, a carbanion derived from a P,y-unsaturated thioether couples with an allylic halide. The... 

Coupling of allylic halides with thioether anions... 

Palladium And/Or Copper-Mediated Cross-Coupling Reactions Between 1-Alkynes And Vinyl, Aryl, 1-Alkynyl, 1,2-Propadienyl, Propargyl And Allylic Halides Or Related Compounds. A Review, Rossi. R. Carpita, A. Beilina, F. Org. Prep. Proceed. Int., 1995, 27, 129... 

As complex 67 outperforms the Fe(0)-ate complexes in rate and yield, shown in the reaction of cyclooctenyl bromide with PhMgBr (full conversion complex 67 <20 min, 81% yield, 38 18 h, 39% yield), it was shown that both Fe(0)-ate and Fe (—2)-ate complexes should be intermediates in cross-coupling reactions, but the major contribution should be made by the route emanating from Fe(—2)-com-plexes. The superiority of Fe(—2)-ate complexes was also shown in the stoichiometric insertion of 67 into allylic halides, which proceeded much faster (<5 min) than with any higher valent iron complex (hours or days). 

The early synthetic processes using organonickel compounds involved the coupling of allylic halides, which react with nickel carbonyl, Ni(CO)4, to give TT-allyl complexes. These complexes react with a variety of halides to give coupling products.255... 

Nickel carbonyl effects coupling of allylic halides when the reaction is carried out in very polar solvents such as DMF or DMSO. This coupling reaction has been used intramolecularly to bring about cyclization of to-allylic halides and was found useful in the preparation of large rings. 

The reductive coupling of allyl halides to 1,5-hexadiene at glassy C electrodes was catalyzed by tris(2, 2,-bipyridyl)cobalt(II) and tris(4,4 -dimethyl-2, 2/-bipyridyl)cobalt(II) in aqueous solutions of 0.1 M sodium dodecylsulfate (SDS) or 0.1 M cetyltrimethylammonium bromide (CTAB).48 An organocobalt(I) intermediate was observed by its separate voltammetric reduction peak in each system studied. This intermediate undergoes an internal redox reaction to form 1,5-hexadiene... 

There are many other transition-metal catalyzed coupling reactions that are based on organic halides in aqueous media. One example is the coupling of terminal alkyne with aryl halides, the Sonogashira coupling, which has been discussed in detail in the chapter on alkynes (Chapter 4). An example is the condensation of 2-propynyl or allyl halides with simple acetylenes in the presence of copper salts. 

It is possible to combine both the type I and the type II situations in the coupling of a chiral aldehyde with a substituted allylic halide. Such is the case in the coupling of unprotected aldoses (e.g., glyceraldehyde)... 

The iron slurries react readily with ethyl a-bromoacetate. The resulting organoiron species adds readily to aldehydes and ketones to produce 3 -hydroxyesters in excellent yields. Addition of a mixture of an aryl aldehyde and an allylic halide to the iron slurry produced good yields of the cross-coupled alcohol. 

COUPLING OF ALLYLIC HALIDES WITH TRIBUTYLTIN CHLORIDE ... 

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