Synthesis of indolocarbazoles via sequential palladium catalyzed cross-coupling and benzannulation reactions

The Synthesis and Applications of Heterocyclic Boronic Acids

“…A variety of natural products that show anti-tumour activity as well as protein kinase C inhibitory properties contain an indolecarbazole motif in their structure. In their 1997 studies Merlic and his group 79,80 prepared the unsymmetrical 2,2′-biindole 59, as substrates for a pivotal benzannulation reaction, via the Suzuki coupling of the boronic ester 58 and 2-iodoindole (Scheme 16). The authors studied the effects of a range of different nitrogen protecting groups upon the subsequent coupling reaction.…”

Simple indole alkaloids and those with a nonrearranged monoterpenoid unit (July 1997 to December 1998)

“…Ring expansion of a furanosylated indolocarbazole to a pyranosylated one made possible the synthesis of (+)-staurosporine 132 as well as the related compounds (+)-RK286c, (+)-MLR-52 and (2)-TAN-1030a. 213 Synthetic studies towards the indolocarbazole skeleton in general have been reported, with use made of chromium carbene complexes, 214 sequential palladium-catalysed crosscoupling and benzannulation reactions, 215 and dimerization of 1-phenylsulfonyl-3-cyanomethylindole. 216 Bisindolylmaleimides, useful in the synthesis of staurosporine and its derivatives, are available in high yield via condensation of indole-3-acetamides and methyl indole-3-glyoxylates.…”

Synthesis of Indole and Biindolyl Triflones: Trifluoromethanesulfonylation of Indoles with Tf2O/TTBP (2,4,6-tri-tert-butylpyridine) System

“…Biindolyls are frequently encountered as structural motifs in pharmaceuticals and functional materials, hence their triflones were focused on. 2,2′-Biindolyls are generally obtained by a metal-mediated coupling reaction . We found the 2,2′-biindolyl triflones to be easily synthesized by a simple base treatment without any help of an organometallic coupling reaction.…”

“…Interestingly, treatment of biindolyl triflone 6a with LiAlH 4 gave a symmetric 2,2′-biindolyl 7 , which was previously synthesized via a metal-mediated coupling reaction (Scheme ). These results indicate that this method provides not only the first synthesis of biindolyl triflones but also a rare example of the preparation of 2,2′-biindolyls without using a metal-mediated coupling reaction …”