Sonogashira-Heck reaction


A modern and very important reaction in organic chemistry is the Heck reaction, i.e. the palladium-catalyzed carbon-carbon bond coupling of an alkyl, aryl or vinyl group to an alkene 1. The actual reactive coupling species is a palladium complex, generated from a halide RX (X = Br or I), which adds to the olefinic substrate. The Heck reaction, just like the Suzuki reaction, the Stille coupling reaction and the Sonogashira reaction, belongs to a family of palladium-catalyzed carbon-carbon coupling reactions of related mechanism.  [c.154]

Closely related to the Heck reaction is the Sonogashira reaction i.e. the palladium-catalyzed cross-coupling of a vinyl or aryl halide 20 and a terminal alkyne 21  [c.158]

Stirring.—It is frequently necessary to stir organic reaction mixtures for comparatively long periods. Magnetic stirrers (see Fig. II, 7, 15) are useful for this purpose provided the viscosity of the reaction mixture is not too high. Inexpensive magnetic stirrers, suitable for semimicro vessels, are available commercially, as are also combined hot plate and magnetic stirring apparatus.  [c.1108]

The original Sonogashira reaction uses copper(l) iodide as a co-catalyst, which converts the alkyne in situ into a copper acetylide. In a subsequent transmeta-lation reaction, the copper is replaced by the palladium complex. The reaction mechanism, with respect to the catalytic cycle, largely corresponds to the Heck reaction.Besides the usual aryl and vinyl halides, i.e. bromides and iodides, trifluoromethanesulfonates (triflates) may be employed. The Sonogashira reaction is well-suited for the synthesis of unsymmetrical bis-2xy ethynes, e.g. 23, which can be prepared as outlined in the following scheme, in a one-pot reaction by applying the so-called sila-Sonogashira reaction  [c.158]

Bromo- and 4-iodopyrazoles do not react with terminal acetylenes under the standard conditions of the Heck-Sonogashira reaction in the presence of organic bases and solvents [82ACS(B)101]. But when the nitrogen atom is substituted, C-alkynylation can occur. If the N substituent can be later removed, it serves as a protecting group for the pyrazole N—H. From the synthetic point of view, the value of a protecting group should be judged by its availability and by its ease of introduction and removal under mild conditions that do not damage other sensitive functionalities.  [c.29]

The condensation of 4-ethynyl-1,3-dimethyl-5-aminomethylpyrazole with iodo-benzene in the standard conditions of the Heck-Sonogashira reaction caused no complications and the yield of disubstituted acetylene was 87% (86TH1) (Scheme 68).  [c.35]


See pages that mention the term Sonogashira-Heck reaction : [c.23]    [c.623]    [c.26]   
Advances in heterocyclic chemistry Vol.85 (2003) -- [ c.23 , c.82 ]