Indium-catalyzed Barbier-type reaction

This indium-mediated palladium-catalyzed Barbier-type allylation of aldehydes is expanded to cascade reactions with allenes, which give three-component coupling products (Tab. 8.12 and 8.13) [89]. 

Iminium ions, generated in aqueous solution from secondary amines and formaldehyde, undergo a Barbier-type allylation mediated by tin, aluminum, and zinc. The reaction is catalyzed by copper and produces tertiary homoallylamines in up to 85% yield.67 The imines generated in situ from 2-pyridinecarboxaldehyde/2-quinolinecarboxaldehyde and aryl amines undergo indium-mediated Barbier allylation in aqueous media to provide homoallylic amines.68 Crotyl and cinnamyl bromides... 

Cooper et al. reported that the cascade reaction of the palladium-catalyzed cyclization and the Barbier-type allylation of the 1,3-diene-aryl iodide 514, the aldehydes 515, and indium gave the heterocycles 516 in good yields (Scheme 154).220b The reaction proceeds through oxidative addition of a C—I bond of 514 to Pd(0) and subsequent insertion of a double bond of 517 to give the jr-allylpalladium intermediate 518. Transmetalation of the jr-allylpalladium 518 with indium leads to the allylindium complex 519, and the following reaction with the aldehydes 515 gives 516. 

For the use of indium catalyzed reactions in organic synthesis, see (a) Chauhan, K.K. Frost, C.G. J. Chem. Soc., Perkin Trans. 1, 2000, 3015. For a list of reagents used in this type of reaction, see (b) Smith, M.B. March, J. March s Advanced Organic Chemistry, 5th ed. Wiley New York, 2001, pp 1205-1211. (c) For reactions of this type, see Reference 26, pp 1126-1133. Also see (d) Blomberg, C. Reactions and Structure. Concepts in Organic Chemistry, Vol. 31. The Barbier Reaction and Related One-Step Processes, Springer Verlag, Berlin, 1993. 

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