Acetylides, cross-coupling with terminal alkynes

The Pd-catalyzed coupling of o-haloanilines and terminal alkynes tends to produce either the 2-(l-alkynyl)aniline or mixtures of the alkynylanilines and the corresponding indoles [17,18]. However, iV-benzyl-2-iodoaniline has recently been cross-coupled with terminal alkynes to afford the corresponding ben-zylindoles using a Pd zeolite catalyst (Eq. 14) [39]. One can also employ stoichiometric amounts of copper acetylides to effect this transformation [22-24]. 

Z-selective cross-coupling of terminal alkynes with isocyanides to exclusively yield (Z)-l-aza-l,3-enyne products has been achieved for the first time using a constrained geometry catalysts [Y(C5Me4Si(Me2)NR)(Alk) (THF)X] (Aik = R, dimethylaminobenzyl R = lBu, Ph, 2,4,6-Me3C6H2. The intermediate was shown to be the acetylide-bridged dimer [Y(C5Me4Si (Me2)NR)(p-C=CPh)]2.41 [24]... 

Wang et al. have discovered that ultrafme Ni powder in the presence of Cul, PPh3, and KOH promotes coupling of terminal alkynes with aryl and alkenyl iodides in high yields [65], Recent developments have shown, moreover, that the use of co-catalysts (Cu, Zn, Al, etc.) to facilitate the formation of the acetylides is not always required and that cross-coupling reactions of acetylenes and aryl halides can be performed successfully with Pd-based catalysts alone, even with difficult substrates [48, 66]... 

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