Selanyl and tellanyl electrophiles as a driving force in the construction of sophisticated polyaromatic hydrocarbons

Abstract

Herein we report the first examples of N-polyaromatic compounds bearing up to 13 fused aromatic rings, including 23H-benzo[12,1]tetrapheno[8,9-b]benzo[12,1]tetrapheno[9,8-h]carbazole derivative. Selanyl and tellanyl electrophiles reaction with ethynyl biphenyls through 6-endo-dig closure...

Recyclable iodine-catalyzed radical selenylative annulation of 2-alkynyl biaryls with diselenides in water: a green approach to selanyl polycyclic aromatic hydrocarbons and polycyclic heteroaromatics

“…A wide variety of selanyl PAHs such as phenanthrenes, benzo [c]phenanthrene, benzo[g] chrysene, and dibenzo [ij,no]tetraphene and also selanyl polycyclic heteroaromatics such as naphtho[2,1-b]thiophene and naphtho[2,1-b]furan were synthesized in moderate to excellent yield. In contrast to the previously reported electrophilic (ionic) selenylative annulations of 2-alkynyl biaryls, [16][17][18] we unveiled and proposed that the reaction mechanism operates through a radical pathway but not through a polar (ionic) pathway, as supported by both experimental and computational studies. The in situ formed phenylselenyl iodide (PhSeI) was found to be more reactive than the commercially available PhSeBr or PhSeCl for the synthesis of selanyl PAHs or polycyclic aromatic hydrocarbons.…”

“…The use of sub-stoichiometric H 2 O 2 is found to be indispensable for the higher atom-economy of the reaction as the use of super-stoichiometric H 2 O 2 may cause higher loading of diphenyl diselenide 2a owing to its favourable oxidation to phenyl selenic acid (PhSeO 3 H) by super-stoichiometric H 2 O 2 . 17 Notably, it has been found that the use of excess H 2 O 2 (5 equiv.) oxidized diphenyl diselenide 2a to phenyl selenic acid (PhSeO 3 H) quantitatively, 17 but the same reaction was not effective at all when only 0.5 equiv.…”

“…17 Notably, it has been found that the use of excess H 2 O 2 (5 equiv.) oxidized diphenyl diselenide 2a to phenyl selenic acid (PhSeO 3 H) quantitatively, 17 but the same reaction was not effective at all when only 0.5 equiv. of H 2 O 2 was used, as evidenced by the 77 Se NMR spectrum of the corresponding reaction mixtures (Fig.…”

“…in dry MeCN under an aerobic atmosphere to synthesize 9-phenylselanylphenanthrenes in good yield (Scheme 1B). 17 This method also suffered from several severe limitations such as very low atom economy, and the requirement of super stoichiometric diphenyl diselenide (2 equiv. ), a hazardous oxidant, m -CPBA (5 equiv.…”

Alkyne‐Based Syntheses of Carbo‐ and Heterohelicenes

“…Selanyl and tellanyl electrophiles, generated from the diphenyldiselenide and diphenylditelluride upon oxidation with m-CPBA or K 2 S 2 O 8 , have been used to transform (2-phenylethynyl)biaryls 35 into [4]helicenes 37, 38 and carbazole-based double [4]helicenes 39-41 (Scheme 9). [63] The reaction proceeded with excellent yields. An attempt to perform the same cyclization with diphenyldisulphide failed.…”