Novel synthesis of 5-methyl-5,10-dihydroindolo[3,2-b]indoles by Pd-catalyzed C–C and two-fold C–N coupling reactions

Abstract

A series of 5,10-dihydroindolo[3,2-b]indoles was successfully prepared by an efficient two-step strategy based on site-selective Pd-catalyzed cross-coupling reaction with N-methyl-2,3-dibromoindole and subsequent cyclization by two-fold Pd-catalyzed C-N coupling with amines. The products show a strong fluorescence.

Cu(OAc)2-Mediated Cascade Annulation of Diarylalkyne Sulfonamides through Dual C–N Bond Formation: Synthesis of 5,10-Dihydroindolo[3,2-b]indoles

“…The indoloindole skeleton can also be assembled through Fischer condensation of indolones with hydrazine derivatives (Scheme , path c) or through the reduction of 6,12-dichloro­dibenzo­[ b , f ]­[1,5]-diazocines in the presence of excess zinc under acidic conditions (Scheme , path d) . Recently, Pd-catalyzed cross-couplings between 2,3-dibromo-1-methyl-1 H -indole, m -bromophenyl-boronic acid, and amines with subsequent cyclization provided a two-step strategy to access this privileged molecule (Scheme , path e) . Although these strategies all have their respective merits in the construction of the indoloindole skeleton, we believe developing additional methods, those being more convenient, efficient, and/or economical, is still in high demand.…”

Structurally Diverse π‐Extended Conjugated Polycarbo‐ and Heterocycles through Pd‐Catalyzed Autotandem Cascades

“…For our study we chose 3‐bromo‐2‐(2‐bromophenyl)‐1‐tosyl‐1 H ‐indole 20 and 3‐bromo‐2‐(2‐bromophenyl)benzo[ b ]thiophene 21 (Scheme ). The required dibrominated indole 20 33 was readily prepared by reaction of N ‐tosyl‐2‐ethynylaniline 22 with 1‐bromo‐2‐iodobenzene34 under typical Sonogashira conditions, which afforded the corresponding indole derivative 23 , followed by bromination with NBS (Scheme ). The benzothiophene analogue 21 was prepared following a known procedure by selective Suzuki cross‐coupling of 2,3‐dibromothiophene with o ‐bromophenylboronic acid 35…”

Multifunctional Heteropentalenes: From Synthesis to Optoelectronic Applications

“…This includes, for example, the synthesis of 5,10-dihydroindolo[3,2- b ]indoles via a double Buchwald–Hartwig amination. 16 The third method, dedicated for the preparation of homoheteroatomic HPs (e.g., DHPP, TT, or SS), involves simultaneous formation of [3,2- b ]-fused heterocyclic cores ( Scheme 1 C, path III) as in the case for the synthesis of TTs. 13 Various straightforward methodologies leading to derivatives and π-expanded analogues of benzothieno[3,2- b ]benzothiophenes include the reaction of (dichloromethyl)benzene with elemental sulfur, fusion of 2-chlorobenzaldehyde with NaSH and oxidative fusion of stilbenes possessing two MeS groups.…”