Electrochemical Synthesis of a Thiophene‐Containing Cyclo[9]pyrrole

Abstract

A new member of the cyclo[n]pyrrole class of expanded porphyrins could be prepared from the corresponding thiophene-containing terpyrrole precursor through use of a mild electrochemical oxidative procedure. The isolated macrocycle, featuring nine heterocyclic subunits directly connected through their α,α'-positions, is the largest cyclo[n]pyrrole derivative reported to date (see figure).

Macrocyclization Reactions: The Importance of Conformational, Configurational, and Template-Induced Preorganization

“…483 Similar results were found for the related precursor (483) of the macrocycle 484 using TBAHSO 4 as the electrolyte ( Figure 150). 484 In the case of the preparation of tetrameric macrocycles obtained from xanthene (X) and biphenyl oxide (D) subunits discussed in section 5.1.3 (see Figure 60), the preparation of the XDDD macrocycle 487 from diamine 485 and diisocyanate 486 was only possible using TBACl in acetonitrile as the solvent. Under these reaction conditions, the Cl − anion templates the macrocyclization reaction allowing obtaining the macrocyclic compound 487 in 25% yield, while it was not possible to obtain the macrocycle 487 in the absence of the template ( Figure 151).…”

Template Synthesis of Decaphyrin without Meso-Bridges: Cyclo[10]pyrrole

“…Sessler, Kim, and Bucher have reported the electrochemical synthesis of a thiophene-containing cyclo[9]pyrrole, cyclo[3]thiophene [6]pyrrole, in 2012. 4 Sessler, Kim, and Ishida have also reported cyclo [6]pyridine [6]pyrrole synthesized by Suzuki−Miyaura cross-coupling in 2014. 5 These are hybrid macrocycles of cyclo [n]pyrrole.…”

[40]π Fused and Nonfused Core‐Modified Nonaphyrins: Syntheses and Structural Diversity

“…For example, 1 reported by Osuka and co‐workers, contain nine meso carbon bridges with 40π electrons while 2 has 38π electrons with six meso carbon bridges and three direct pyrrole–pyrrole links . Macrocycle 3 has no meso bridges and has 34π electrons . The chemistry of nonaphyrins has not been explored to its full potential owing to synthetic difficulties, poor yield of the reaction, and conformational flexibility of the macrocycles.…”

“…Osuka and co‐workers used oxidative coupling of tripyrromethanes to synthesize 2 , while the ring‐size‐selective synthesis from the methanesulfonic acid catalyzed reaction of tripyrromethane with aryl aldehydes yield 1 along with hexaphyrin ,. Compound 3 was synthesized through a mild electrochemical oxidative method using thiophene‐containing precursor . Herein, we report the synthesis of two kinds of nonaphyrins ( 6 and 10 ) using an acid‐catalyzed condensation of appropriate precursors.…”