A facile and general approach to the synthesis of 2,5,7-trisubstituted indoles from readily available 2-bromo-6-iodo-4-substituted and 2-bromo-4-chloro-6-iodoanilines is reported. The assembly of the indole rings is accomplished via a one-pot Sonogashira cross-coupling with terminal alkynes followed by a palladium-catalyzed cyclization step. The functionalization at C7 and at C5 (with indoles bearing a chloro substituent at C5) is carried out by alkynylations, Suzuki-Miyaura cross-couplings, and Buchwald-Hartwig C-N bond forming reactions. One-pot protocols for the synthesis of 2,5,7-trisubstituted indoles from 2-aryl-7-bromo-5-chloroindoles as well as from 2-bromo-4-chloro-6-iodoaniline are also described.
Cacchi, S., Fabrizi, G., Goggiamani, A., Iazzetti, A., Verdiglione, R., A facile palladium-catalyzed route to 2,5,7-trisubstituted indoles, <<TETRAHEDRON>>, 2015; 71 (49): 9346-9356. [doi:10.1016/j.tet.2015.10.002] [http://hdl.handle.net/10807/200523]
A facile palladium-catalyzed route to 2,5,7-trisubstituted indoles
Iazzetti, Antonia
;
2015
Abstract
A facile and general approach to the synthesis of 2,5,7-trisubstituted indoles from readily available 2-bromo-6-iodo-4-substituted and 2-bromo-4-chloro-6-iodoanilines is reported. The assembly of the indole rings is accomplished via a one-pot Sonogashira cross-coupling with terminal alkynes followed by a palladium-catalyzed cyclization step. The functionalization at C7 and at C5 (with indoles bearing a chloro substituent at C5) is carried out by alkynylations, Suzuki-Miyaura cross-couplings, and Buchwald-Hartwig C-N bond forming reactions. One-pot protocols for the synthesis of 2,5,7-trisubstituted indoles from 2-aryl-7-bromo-5-chloroindoles as well as from 2-bromo-4-chloro-6-iodoaniline are also described.
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