Rapid pseudo five-component synthesis of intensively blue luminescent 2,5-di(hetero)arylfurans via a Sonogashira–Glaser cyclization sequence

Abstract

Summary2,5-Di(hetero)arylfurans are readily accessible in a pseudo five-component reaction via a Sonogashira–Glaser coupling sequence followed by a superbase-mediated (KOH/DMSO) cyclization in a consecutive one-pot fashion. Besides the straightforward synthesis of natural products and biologically active molecules all representatives are particularly interesting due to their bright blue luminescence with remarkably high quantum yields. The electronic structure of the title compounds is additionally studied with DFT computations.

Palladium‐Catalyzed Cross‐Coupling of Furfuryl Alcohols with Arylboronic Acids via Aromatization‐Driven Carbon−Carbon Bond Cleavage to Synthesize 5‐Arylfurfuryl Alcohols and 2,5‐Diaryl Furans

“…Because a number of compounds with 2,5-diaryl furan moieties have remarkable bioactivities and high luminescence efficiencies, [8,9] we explored the use of the above-described CÀ C bond cleavage reaction for the synthesis of 2,5-diaryl furans 3 from (5-(m-tolyl) furan-2-yl)methanol 2 bi', which was obtained by deprotection of 2 bi (see SI for details). Because a number of compounds with 2,5-diaryl furan moieties have remarkable bioactivities and high luminescence efficiencies, [8,9] we explored the use of the above-described CÀ C bond cleavage reaction for the synthesis of 2,5-diaryl furans 3 from (5-(m-tolyl) furan-2-yl)methanol 2 bi', which was obtained by deprotection of 2 bi (see SI for details).…”

“…Arylfurans, including 2-arylfurans and 2,5-diaryl furans, which have interesting bioactivities [8] and physical properties, [9] are usually synthesized by construction of the furan ring from alkynes [10] or by cross-coupling reactions of environmentally unfriendly halides or organotin reagents. [11] Recently, Forgione and co-workers described palladium-catalyzed decarboxylative cross-coupling reactions of sustainably sourced 2,5-furandicarboxylic acid with aryl halides to access symmetric 2,5-diaryl furans, although the reaction conditions were harsh.…”

Sequentially Palladium-Catalyzed Processes in One-Pot Syntheses of Heterocycles

“…This sequence was employed as an entry to a pseudo five-component synthesis of symmetrically substituted 2,5-di(hetero)arylthiophenes 19 (Scheme 12) [85]. Likewise, the Müller group disclosed a rapid access to intensively blue luminescent 2,5-di(hetero)arylfurans when potassium hydroxide was used as the bifunctional nucleophile [86]. The same concept was applied to the synthesis of 3-(hetero)arylmethyl-2,5-di(hetero)aryl-substituted thiophenes in the sense of a pseudo five-component process by employing (hetero)aryl methylthiols as masked dinucleophilic substrates [87].…”

Thiophene-forming one-pot synthesis of three thienyl-bridged oligophenothiazines and their electronic properties

“…As part of our concept to develop novel multicomponent strategies for the synthesis of functional π-electron systems [73], we reasoned that our recently reported one-pot consecutive Sonogashira–Glaser sequence [74] and the resulting application to pseudo five-component syntheses of 2,5-di(hetero)arylthiophenes [75–76] as well as intensively blue luminescent 2,5-di(hetero)arylfurans [77] could open a highly convergent thiophene forming approach to the proposed title compounds. Here, we report the pseudo five-component synthesis of three thienyl-bridged oligophenothiazines by a one-pot Sonogashira–Glaser cyclization sequence and the electronic characterization by electronic spectroscopy, cyclic voltammetry, and quantum chemical computations.…”