Allyl halides alkynylation

Allylation of perfluoroalkyl halides with allylsilanes is catalyzed by iron or ruthenium carbonyl complexes [77S] (equation 119) Alkenyl-, allyl-, and alkynyl-stannanes react with perfluoroalkyl iodides 111 the presence ot a palladium complex to give alkenes and alkynes bearing perfluoroalkyl groups [139] (equation 120)... 

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. ... 

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... 

Nozaki-Hiyama-Kishi (NHK) reactions215,216 are well known and often employed as a useful method for the synthesis of natural products by coupling of allyl, alkenyl, alkynyl, and aryl halides or triflates with aldehydes. The organochromium reagents are prepared from the corresponding halides or triflates and chromium(ll) chloride, and are employed in polar aprotic solvents (THF, DMF, DMSO, etc.). Subsequently, it was found that nickel salts exhibited a significant catalytic effect on the formation of the C-Cr bond217,218 (Equation (19)). 

Pentafluorophenylcopper exhibits high reactivity towards a variety of organic substrates such as aryl, vinyl, alkynyl, allyl halides etc. [226,227,229,235-238] (Scheme 77). Similar to trifluorovinylcopper, pentafluorophenylcopper readily adds to hexafluoro-2-butyne to form the syn addition product, which can be quenched with electrophiles [230] (Scheme 78). 

Reaction of methyl iododifluoroacetate with copper in HMPA affords the carboalkoxydifluoromethylene copper reagent, which couples with aryl, alkenyl, alkyl, alkynyl and allyl halides to give the corresponding 2,2-difluoroester derivatives [261] (Scheme 87). 

CH3 CH2 CH=CHC1]. In those cases where the halogen is attached to an sp-hybridised carbon atom in an alkyne, the compounds are called alkynyl (or acetylenic) halides [R C C X, e.g. 1-bromobut-l-yne (3) CH3 CH2 C=CBr], Allylic halides (R CH=CH CH2X) have an sp2-hybridised carbon atom attached to a saturated halogen-carrying carbon [e.g. (E)- l-iodobut-2-ene (4) CH3-CH=CH-CH2I]. 

R. Rossi, A. Carpita, F. Beilina, 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, Org. Prep. Proced. Int. 1995, 27, 127-160. 

This method applies to aryl, alkenyl, allyl and alkynyl halides as well as to alkenyl Inflates and exhibits the same selectivity profile as its stoichiometric precedent (Scheme 4). Moreover, it does not matter if the catalytic cycle is started at the Cr or Cr " stage as implied by Scheme 3. Therefore it is possible to substitute cheap and stable CrClj for the expensive and air-sensitive CrCf previously used for Nozaki reactions. In some cases other chromium templates such as [Cp2Cr or [CpCrCl2] can be employed, improving the total turnover number of this transformation even further [13, 14]. 

Reaction with an amine, AIBN, CO and a tetraalkyltin catalyst also leads to an amide.Benzylic and allylic halides were converted to carboxylic acids electroca-talytically, with CO and a cobalt imine complex. Vinylic halides were similarly converted with CO and nickel cyanide, under phase-transfer conditions.Allylic (9-phosphates were converted to allylic amides with CO and ClTi=NTMS, in the presence of a palladium catalyst. Terminal alkynes were converted to the alkynyl ester using CO, PdBr2, CuBr2 in methanol and sodium bicarbonate. ... 

The overall reaction makes it possible to perform intramolecular caibozincations [65-71] via a radical cyclization. This useful preparation of cyclopentylmethylzinc derivatives proceeds with excellent stereoselectivity and allows preparation of quaternary centers. After cyclization, the zinc organometallic can be transmetallated with CuCN-2LiCl and made to react with a broad range of electrophiles such as acid chlorides, allylic and alkynyl halides, ethyl propiolate, 3-iodo-2-cyclohexen-l-one, and nitroolefins such as nitrostyrene, leading to products of type 40 (see Section 9.6.9 Scheme 9-34) [65,70]. 

Many alkynyl, alkenyl, aryl, and functionalised alkyl-lithiums behave well in alkylation reactions because they are more stable anions than those derived from the simple unfunctionalised alkyl halides with which they are to react. Examples are 24, 25, and 26 and these will be treated in later chapters with the reactions of Grignard reagents with allyl halides. 

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