Alkenyl halides alkynylation

At equilibrium, therefore, the Li becomes attached preferentially to the organic group best able to stabilize the negative charge. Hence, extensive exchanges and useful preparations are available from reaction of alkyl Li with aryl halides, cyclopropyl halides, alkenyl halides, alkynyl halides and a-heterosubstituted alkyl halides (including per- and polyhaloalkanes), but not with simple alkyl halides e.g., interaction of EtLi and Mel provides a mixture of EtLi and MeLi. 

Other pseudo-halides are used for carbonylation. Phenyl tluorosulfonate (484) can be carbonylated to give benzoate[337]. Aryl(aryl)iodonium salts[338], aryl(alkenyl)iodonium salts (485)[339], and arylialkynyl)iodonium salts (486)[340] are reactive compounds and undergo carbonylation under mild conditions (room temperature, 1 atm) to give aryl, alkenyl, and alkynyl esters. lodoxybenzene (487) is carbonylated under mild conditions in... 

Palladium-catalyzed carbon-carbon bond forming reactions like the Suzuki reac-tion as well as the Heck reaction and the Stille reaction, have in recent years gained increased importance in synthetic organic chemistry. In case of the Suzuki reaction, an organoboron compound—usually a boronic acid—is reacted with an aryl (or alkenyl, or alkynyl) halide in the presence of a palladium catalyst. 

Catalyst 11 showed great tolerance for functional groups like rmsaturated carbon-carbon bonds (alkenyl and alkynyl moieties), halides, electron-withdrawing and -donating groups, etc. (Table 4). 

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). 

General methods of preparation for alkenyl and alkynyl halides are listed in Table 14-5. By the alkynyl halides we mean 1-halo-alkynes. One interesting method by which they may be prepared employs 1-alkynes with hypohalites ... 

As organotin compounds (organostannanes) undergo smooth Pd-catalysed transmetallation, aryl halides react with a wide variety of aryl-, alkenyl- and alkylstannanes [139]. Coupling with allylstannane is the first example [140]. The reaction is called the Migita-Kosugi-Stille or Stille coupling. Aryl, alkenyl, allyl, alkynyl and benzyl... 

The Suzuki Coupling, which is the palladium-catalysed cross coupling between organoboronic acid and halides. Recent catalyst and methods developments have broadened the possible applications enormously, so that the scope of the reaction partners is not restricted to aryls, but includes alkyls, alkenyls and alkynyls. Potassium trifluoroborates and organoboranes or boronate esters may be used in place of boronic acids. Some pseudohalides (for example triflates) may also be used as coupling partners. 

Alkynyl(methoxy)borates prepared in situ from an alkynyllithium or sodium and 9-methoxy-9-BBN coupled with 1-alkenyl and aryl halides (Equation (210)).899-902 Addition of triisopropylborate to lithium acetylide yielded an air stable and isolable ate complex that couples with aryl and alkenyl halides (Equation (211)).903 904 Air and moisture stable alkynyltrifluoroborates were probably the most convenient reagents that allow handling in air and coupling reactions in basic aqueous media (Equation (212)).46... 

Alkynyl(trimethyl)silanes smoothly couple with alkenyl halides at room temperature in the presence of a palladium catalyst and TASF (Eq. 5) [4]. The difference in reactivity between alkynylstannanes and -silanes were utilized in a palladium-catalyzed three component cross-coupling reaction. Thus, the palladium-catalyzed sequential reaction of tributylstannyl(trimethylsilyl)ethyne... 

On the other hand, it is well known that stereodefined 1-alkyenyldialkylboranes are readily prepared by the monohydroboration of alkynes, i.e. dialkylboranes such as disiamylborane and catecholborane permit the monohydroboration of terminal alkynes, thus making readily available the corresponding (E)-l-alkenyldialkyl-boranes with high stereoselectivity, more than 99% (Eq. 97) . Highly pure (Z)-l-alkenyldialkylboranes (purity, more than 98%) are prepared without any difficulty via the monohydroboration of 1-halo-1-alkynes with disiamylborane or dicyclohexylborane, followed by treatment with t-butyllithium (Eq. 98) Consequently, if such 1-alkenyldialkylboranes react with 1-alkenyl halides or 1-alkynyl... 

Transmetalation to Cu, Ni, or Zn is sometimes necessary to release the organic compounds. For instance, treatment of zirconacyclopentadiene with CuCl generates an unstable dicopper complex, which can couple in situ with allyl, benzyl, aryl, thienyl, alkynyl, and alkenyl halides (Scheme 32). ... 

Physical and chemical data on the MR2L, (R = Me, Et, Ph, allyl, alkenyl, and alkynyl) and MXR(L) (R = Bu, Ph, tolyl X = halide) compounds are greatly lacking, owing to these compounds generally poor thermal stability. The aryl MXR(L) and alkynyl MR2L compounds constitute the most stable classes.The compounds decrease in stability Ba < Sr and XR(L),j compounds form most readily for — I... 

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