N‐Arylation of Diketopyrrolopyrroles with Aryl Triflates

Abstract

A new methodology for the double N-arylation of diketopyrrolopyrroles with aryl triflates has been developed. It is now possible to prepare diketopyrrolopyrroles bearing Nsubstituents derived from naphthalene, anthracene and coumarin in two steps from commercially available phenols. This represents the first time arenes lacking strong electronwithdrawing groups were inserted onto lactamic nitrogen atoms via arylation. The ability to incorporate heretofore unprecedented substituents translates to increased modulation of the resulting photophysical properties such as switching-on/off solvatofluorochromism. TD-DFT calculations have been performed to explore the nature of the relevant excited states. This new synthetic method made it possible to elucidate the influence of such substituents on the absorption and emission properties of tetraaryl substituted diketopyrrolopyrroles.

New Synthetic Approaches toN‐Aryl and π‐Expanded Diketopyrrolopyrroles as New Building Blocks for Organic Optoelectronic Materials

“…After the reaction mixtures were stirred for 12 h in air, N ‐aryl DPPs of different structures ( 3 a – 3 p , Scheme 1) were obtained in 29–78 % yields after separation. Obviously, this synthetic approach toward N ‐aryl DPPs is different from those reported previously [4–7] . These N ‐aryl DPPs bear different flanking aryl groups, such as phenyl, furan and thiophene, which are linked to the central DPP core at either 2‐ or 3‐ positions, and moreover the N ‐aryl groups in N ‐aryl DPPs entail no electron‐withdrawing groups.…”

“…In this paper, we firstly report a new easily handled synthetic method toward N ‐aryl DPPs, by using the reaction of H‐DPP with diaryliodonium salt [12] in the presence of CuI as the catalyst in air (see Scheme 1). The reaction scope is relatively broad in comparison with the reported synthetic approaches [4–7] for N ‐aryl DPPs. Sixteen N ‐aryl DPPs, in which the flanking aromatic groups are phenyl, furan and thiophene, were successfully synthesized with this newly developed method in acceptable yields.…”

“…N ‐alkyl DPPs are easily accessible from 3,6‐diaryl‐2,5‐dihydropyrrolo[3,4‐ c ]pyrrole‐1,4‐dione (H‐DPP), which is commercially available [2f, 3–6] . In comparison, the synthesis of N ‐aryl DPPs has received limited success [4–7] . Langhals and co‐workers reported the preparation of N ‐aryl DPPs through the condensation of anilines with diphenyl‐1,4‐dihydrofuro‐[3,4‐ c ]furan‐1,4‐dione, [5] which, however, is poorly accessible.…”

“…But, the aryl halides with electron withdrawing groups are needed, and thus the reaction scope is narrow and this synthetic path to N ‐aryl DPPs is not very practicable. Recently, Gryko, Jacquemin and co‐workers have reported the synthesis of N ‐aryl DPPs by the Pd II catalyzed reaction between H‐DPP and naphthalene/anthracene/coumarin triflates [7] . It is noted that biaryl phosphine JackiePhos is expensive.…”

How To Make Nitroaromatic Compounds Glow: Next‐Generation Large X‐Shaped, Centrosymmetric Diketopyrrolopyrroles

“…The ubiquitous presence of bis-Nalkylated DPPs [8,10,22] contrasts with the scarcity of bis-Narylated DPPs. [23][24][25] The most intuitive approach is based on the reaction between DPP and the corresponding aryl fluoride in the presence of a base. Thus, to accomplish our goal, we began by testing the activity of commercially available 3-bromo-4fluoronitrobenzene for the arylation of DPP.…”