A direct synthesis of indolocarbazoles via new dinitroterphenyl precursors

Abstract

The two indolocarbazoles 2 and 4 were synthesized via the reductive ring closure of dinitrodiphenylbenzenes with triethylphosphite as reducing agent in a high boiling solvent. The electrochemical behaviour of the title systems is discussed.

1,4,9,12-Tetramethoxy-14-octyl-5,8-dihydrodiindolo[3,2-b;2′,3′-h]carbazole with an unknown solvent

“…Among the different synthetic routes (Vlasselaer & Dehaen, 2016), the twofold Cadogan reaction (Cadogan et al, 1965) is a very successful route to indolocarbazoles (Kistenmacher & Mü llen, 1992;Wrobel et al, 2013) and is also suitable for the preparation of higher oligomers (Srour et al, 2016). In a continuation of our studies on indolo-annulated heterocycles (Dassonneville et al, 2011;Nissen & Detert, 2011;Letessier & Detert, 2013), we present here the first X-ray structure of a linear diindolocarbazole (Fig.…”

Synthesis of Linearly Fused Benzodipyrrole Based Organic Materials

“…First, they prepared terphenyl compound 53 by performing a double Suzuki coupling on 1,4-dibromo-2,5-dinitrobenzene 51 and phenylboronic acid 52 in 61% yield. Then, the double Cadogan ring closure was performed to obtain the final compound 54 (Scheme 15) [41]. For another example see Leclerc et al [42].…”

Towards the Synthesis of Ladder Oligo(p-aniline)s

“…These methods suffer from low yields, [27][28][29] and/or the formation of side-products (isomers), 28 or long route to obtain the precursor (indole derivatives). 30,31 The insolubility of indolocarbazoles in common organic solvents is responsible of these isolation problems and low yields.…”

“…The synthesis of the [3,2-b]indolocarbazole derivatives which correspond to the phenyl-capped dimers (n = 1 in Scheme 1, a), are already described in the literature using different synthetic approaches. These methods suffer from low yields, [27][28][29] and/or the formation of side-products (isomers), 28 or long route to obtain the precursor (indole derivatives). 30,31 The insolubility of indolocarbazoles in common organic solvents is responsible of these isolation problems and low yields.…”

“…Moreover, we also attempted to synthesize the indolo[3,2b]carbazole with a double Cadogan cyclization on 2¢,5¢dinitro-1,1¢;4¢,1¢¢-terphenyl with triethyl phosphite as already described in the literature, 29 but we were unable to isolate a pure product. Following these results, we believe that the double ring-closure Cadogan reaction realized on 1,4-diaryl-2,5-dinitrophenyl derivatives is difficult.…”