Sakamoto-Yamanaka indole synthesis

The cyclization of oalkynylanilines to indoles, which usually does not require palladium, has been described in Section 3.4. In view of their extensive research with this transformation, this reaction is often referred to as the Sakamoto-Yamanaka indole synthesis [211, 214-216, 220, 230, 231]. Although the cyclization of o-alkynylanilines, which are often obtained by the Sonogashira coupling (Section 3.4), is usually accomplished with base, Kundu used Pd(OAc)2 to effect the conversion of 348 to 349 [308]. 

Scheme 1 Yamanaka-Sakamoto-Sonogashira Indole Synthesis...

The Larock indole synthesis is the internal alkyne version of the Yamanaka-Sakamoto-Sonogashira indole synthesis presented in Chapter 75. Also known as the Larock heter-oannulation, it affords 2,3-disubstituted indoles, in contrast to 2-snbstituted indoles from the Sonogashira reaction (Scheme 1, eqnations 1-3) [1-12], Like the Sonogashira, the Larock reaction has been of enormous utility in indole synthesis. With unsymmetrical alkynes, the regiochemistry is such that the more bulky group (e.g., t-butyl relative to... 

Carbon-carbon bond formation in heterocycles using Ni- and Pd-catalysed reactions , Kalinin, V. N., Synthesis, 1992, 413 Transition metals in the synthesis and functionalisation of indoles , Hegedus, L. S., Angew. Chem., Int. Ed. Engl., 1988, 27, 1113 Synthesis of condensed heteroaromatic compounds using palladium-catalysed reactions , Sakamoto, T., Kondo, Y., and Yamanaka, H., Heterocycles, 1988,27, 2225. 

Palladium-Catalyzed Indole Ring Synthesis Yamanaka-Sakamoto-Sonogashira... 

The Cacchi synthesis of indoles via the Pd-catalyzed cyclization of 2-aIkynylaniUnes and subsequent functionalization has extended enormously the original Yamanaka-Sakamoto-Sonogashira and Larock reactions. For a review of these methods see Beller [41]. 

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