ChemInform Abstract: Cycloisomerization of 2‐Alkynylanilines to Indoles Catalyzed by Carbon‐Supported Gold Nanoparticles and Subsequent Homocoupling to 3,3′‐Biindoles.

Abstract

Cycloisomerization of 2-Alkynylanilines to Indoles Catalyzed by Carbon-Supported Gold Nanoparticles and Subsequent Homocoupling to 3,3'-Biindoles. -The cycloisomerization of 2-alkynyl substituted anilines (I) is studied using a heterogeneous gold on carbon catalysts. Slightly modified conditions with higher Au loadings and pretreatment with HNO3/HCl allows direct synthesis of 3,3'-biindoles as well as the cyclooctatetraene. -(PEREA-BUCETA, J. E.; WIRTANEN, T.; LAUKKANEN, O.-V.; MAEKELAE, M. K.; NIEGER, M.; MELCHIONNA, M.; HUITTINEN, N.; LOPEZ-SANCHEZ*, J. A.; HELAJA, J.; Angew. Chem., Int. Ed. 52 (2013) 45, 11835-11839, http://dx.doi.org/10.1002/anie.201305579 ; Dep. Chem., Univ. Liverpool, Liverpool L69 7ZD, UK; Eng.) -Mais 14-128

Gold-catalysed reactions of diynes

“…The groups of Lopez-Sanchez and Helaja in a collaboration developed a combination of a cycloisomerisation of 2-alkynylanilines to indoles with an oxidative homocoupling to 3,3 0 -biindoles. 21 When using diyne 29, the eight-membered central ring is formed from two molecules of the starting material (Scheme 11), the connectivity of 30 was confirmed by an X-ray single crystal structure analysis. The detailed mechanism is unknown, since in this case of heterogeneous gold catalysis, one can assume that sites with gold(I) or gold(III) character 22 induce the cycloisomerisation and the dehydrogenative C-C coupling is done by the nanoparticle as a whole.…”