Arylation, of alkynes

Hydroarylation, (addition of H-Ar, Ar = aryl), of alkynes, catalysed by Pd(OOCCH3)2 or Pd(OOCCFj)j in acetic acid, is an atom-economic reaction, giving rise to substituted c/i-stilbenes (Fujiwara reaction). Catalytic conversions and improved chemoselectivity to the mono-coupled product under mild conditions can be achieved by modification of the metal coordination sphere with NHC ligands. Hydroarylation of mesitylene by ethylpropiolate (Scheme 2.19) catalysed by complex 107 (Fig. 2.18) proceeds in good conversions (80-99%, 1 mol%) under mild conditions at room temperature. 

Arylation of alkynes via addition of arylboronic acids to alkynes represents an attractive strategy in organic synthesis. The first addition of arylboronic acids to alkynes in aqueous media catalyzed by rhodium was reported by Hayashi et al.89 They found that rhodium catalysts associated with chelating bisphosphine ligands, such as 1,4-Ws(diphenyl-phosphino)butane (dppb) and 1,1 -/ E(diphenylphospliino)fcrroccnc... 

Table 5.11. Alkylation and arylation of alkynes on insoluble supports.

No formula is given for Cacchi s palladium-catalyzed arylation of alkynes with aryl tri-flates as it proceeds mechanistically in analogy with the Sonogashira-Hagihara arylation. 

Alkenylations of alkynes (Figures 13.23 and 13.24) are the methodological supplement to the arylation of alkynes (Figure 13.22). The substrates of the coupling in Figure 13.23 are an alkenyl triflate (preparation analogous to Figure 10.20) and an alkyne... 

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