Catalysis palladium-catalyzed alkynylation

Jones, L.A., Sanz, S. and Laguna, M. (2007) Gold compounds as efficient cocatalysts in palladium-catalyzed alkynylation. Catalysis Today, 122(3-4), 403-406. 

Waser reported in 2013 a highly selective palladium-catalyzed C2-alkynylation reaction of IH-indoles with TIPS-EBX 10 (Scheme 38) (2013OL112). This is complementary to the C3-regioselectivity observed under gold catalysis (see Scheme 7). A broad set of substituted 1-alkylated IH-indoles were alkynylated (19 82) in moderate to good yield under... 

Larock developed a powerful approach to isoquinolines which involves copper-catalyzed hydroamination of A -ferf-butyl-2-(l-alkynyl)benzaldimine accompanied by elimination of ferf-butyl group (Eq. 4) [55-59]. Asao and Yamamoto reported a novel synthesis of 1,2,3-trisubstituted isoquinolines through attack of a carbon nucleophile to the carbon-nitrogen double bond of iV-alkyl-2-(l-alky-nyl)benzaldimine and simultaneous hydroamination catalyzed by transition metal [60]. They also achieved isoquinoline synthesis by transition metal-free three-component coupling (Eq. 5) [61]. Takemoto and Yanada reported a related isoquinoline formation by a catalysis of carbophilic Lewis acids such as indium(III), Ni(II), or Au(I)/Ag(I) [62, 63]. Oikawa succeeded in palladium-catalyzed three-component... 

By the choice of the enyne substrates, the obtained cyclized products might contain functionalities other than dienes. The unusual catalyst combination of a Pd precatalyst and formic acid enables sequential catalysis initiated by cycloisomerization in a very peculiar way. Kressierer and Muller [16] demonstrated in several cases that the palladium(0)-catalyzed Alder-ene reaction of a-alkynyl M-allyl alcohols 7 furnishes cyclic y,5-enals 8 as a consequence of the in situ enol-aldehyde tautomerism (Scheme 12.2). 

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