Ir^III‐Catalyzed One‐Pot Cascade Synthesis of Pentacyclic‐Fused Carbazoles from Indoles and Diazoes

Abstract

A highly efficient Ir -catalyzed cascade cyclization of indoles and diazoes giving access to unique pentacyclic-fused carbazoles has been developed. This novel strategy expanded the application scope of coupling partners to take diazo compounds as a C2 source, and two new cycles, three new C-C and one new C-N bonds were formed in one-pot.

Cascade reaction based synthetic strategies targeting biologically intriguing indole polycycles

“…In the last decade, a number of exquisite cascade reaction routes to polycyclic indoles have been realized using transition metal catalysis. 20,32,[88][89][90] We observed that the majority of these cascade reactions exploit alkyne substrates to form indole polycycles and exploit different modes of catalytic transformations. Therefore, in the following sections, we have categorized the transition metal-catalysed cascade synthesis of indole polycycles based on non-alkyne and alkyne substrates employed in the cascade reactions.…”

Diazo Compounds: Versatile Synthons for the Synthesis of Nitrogen Heterocycles via Transition Metal‐Catalyzed Cascade C–H Activation/Carbene Insertion/Annulation Reactions

“…In 2016, Dong and co‐workers reported an Ir‐catalyzed cascade cyclization of indoles 90 and diazo compounds to afford pentacyclic‐fused carbazole derivatives 94 (Scheme ) . Various alkyl α‐diazoacetoacetates reacted smoothly to provide the target products in good yields.…”

Rh(III)-Catalyzed Cascade C-H Activation/Annulation of Cyclic 2-Diazo-1,3-diketones with Benzoylacetonitriles to Polycyclic Benzo[de]chromenes

“…[13][14][15][16][17][18] In particular, Rh-, Ru-, or Ir-catalyzed C-H activation and subsequent intramolecular cyclization of aromatic compounds with alkynes, or diazo compounds have provided a number of efficient methods for the synthesis of fused (hetero)cyclic compounds. [19][20][21] In this aspect, Miura's group 22 and Ackermann's group 23 respectively described an alternative synthesis of benzo[de]chromene derivatives through Rh-or Ru-catalyzed C-H activation/annulation of 1-naphthols with alkynes (Scheme 1a). Subsequently, Wang and co-workers successfully developed rhodium-catalyzed sequential C-H functionalization of benzoylacetonitriles and tandem intramolecular annulation with alkynes to produce substituted benzo[de]chromanes (Scheme 1b).…”

“…enhance the product formation (Table1, entries[14][15][16][17][18][19]. Moreover, both decreasing and increasing the additive loading could not improve the yield (Table1, entries21,22). Further studies showed that decreasing either the reaction temperature or the reaction time was detrimental to the yield (Table1, entries[23][24][25][26].…”