[Cp*IrCl₂]₂-Catalyzed Indirect Functionalization of Alcohols:  Novel Strategies for the Synthesis of Substituted Indoles

Abstract

We report novel iridium(III)-catalyzed reactions that afford substituted indoles via the indirect functionalization of alcohols via C-3 selective alkylation of indoles with alcohols and a one-pot cascade strategy from amino- or nitro-phenyl ethyl alcohols, which incorporates oxidative cyclization and C-3 alkylation.

Selective Ruthenium‐Catalyzed Alkylation of Indoles by Using Amines

“…On the one hand, reaction of intermediate 2 with a second molecule of indole leads to the bis(3-indolyl)methane species 3, [21] also reported by the group of Grigg. [4] On the other hand, the formation of small amounts of 2,3'-biindole are observed.…”

“…[3] In contrast to these alkylations, transition-metal-catalyzed methodologies have been rarely exploited. In this respect, the recent work of Grigg et al [4] is noteworthy, they achieved good yields by applying mainly benzylic alcohols as alkylation reagents. This reaction is based on the so-called "borrowing hydrogen methodology".…”

Heterometallic complexes, tandem catalysis and catalytic cooperativity

“…With this in mind, we used the Ir-Pt complex Scheme 11 Fig. 1 Comparison between the catalytic activity of the heterodimetallic complex 5, and the mixture of the related homodimetallic complexes of Ir (28) and Pd (29). The products were obtained according to the reactions depicted in Scheme 10.…”

Transition‐Metal‐Catalyzed Hydrogen‐Transfer Annulations: Access to Heterocyclic Scaffolds

“…(19)]. [33] As ustainable approach for the synthesis of pyrroles was developed from the condensation of renewable secondary alcohols with 1,2-amino alcohols using moisture-and airstable crystalline tridendate ligands with iridium (63; Scheme 8). Acceptorless dehydrogenation initially starts with secondary alcohol derivatives followed by base-promoted condensation to afford the imine intermediate 65,w hich undergoes dehydrogenative electrophilic cyclization to lead to formation of pyrrole derivatives (67), with ad iversity of substituents,u nder mild reaction conditions and in good yields.I nterestingly, 63 was also successfully utilized for N-alkylation of the aniline derivatives 68 through aborrowing hydrogen reaction and subsequent hydrogen-transfer condensation with 1,2-amino alcohols to form 3-amino-substituted pyrroles (69)i nvery good yields [Eq.…”