Boron in disguise: the parent "fused" BN indole

Abstract

"Fused" BN indoles are an emerging class of boron-containing indole mimics, featuring geometric structure and electophilic aromatic substitution reactivity similar to those of indoles but exhibiting distinct electronic structure, leading to unique optoelectronic properties. Herein we report the synthesis of the parent N-H BN indole and provide a head-to-head comparison of the structural features, pK(a) values, and optoelectronic properties of this hybrid organic/inorganic indole with the classic natural indole.

Figure 1

Cyclic voltammograms of BN indole 3a and indole 1a (0.08 M TBAOTf in CH₃CN at glassy carbon electrode; scan rate: 50 mV/s).

Figure 2

Normalized absorption (dotted line) and emission (solid line) spectra of BN indole 3a (red) and indole 1a (black) and photo-physical data for 3a and 1a in CH₃CN. ^a Literature value, see reference . ^b Literature value, see reference .

Scheme 1

Synthesis of Parent BN Indole 3a