Contributing to Biochemistry and Optoelectronics: Pyrrolo[1′,2′:2,3]imidazo[1,5-<i>a</i>]indoles and Cyclohepta[4,5]pyrrolo[1,2-<i>c</i>]pyrrolo[1,2-<i>a</i>]imidazoles via [3+2] Annulation of Acylethynylcycloalka[<i>b</i>]pyrroles with Δ¹-Pyrrolines

Abstract

Available pyrrolylalkynones with tetrahydroindolyl, cycloalkanopyrrolyl, and dihydrobenzo[g]indolyl moieties, acylethynylcycloalka[b]pyrroles, are readily annulated with Δ1-pyrrolines (MeCN/THF, 70 °C, 8 h) to afford a series of novel pyrrolo[1′,2′:2,3]imidazo[1,5-a]indoles and cyclohepta[4,5]pyrrolo[1,2-c]pyrrolo[1,2-a]imidazoles functionalized with an acylethenyl group in up to an 81% yield. This original synthetic approach contributes to the arsenal of chemical methods promoting drug discovery. Photophysical studies show that some of the synthesized compounds, e.g., benzo[g]pyrroloimidazoindoles, are prospective candidates for TADF emitters of OLED.

Keywords

• acylethynylcycloalka[<i>b</i>]pyrroles
• Δ¹-pyrrolines
• [3+2] annulation
• pyrrolo[1′,2′:2,3]imidazo[1,5-<i>a</i>]indoles
• cyclohepta[4,5]pyrrolo[1,2-<i>c</i>]pyrrolo[1,2-<i>a</i>]imidazoles