Synthetic methodologies for the construction of selenium-containing heterocycles: a review

Synthetic Potential of Regio- and Stereoselective Ring Expansion Reactions of Six-Membered Carbo- and Heterocyclic Ring Systems: A Review

“…Selenium-incorporated heterocycles have gained considerable significance due to their significant biological applications and extraordinary chemical properties [ 66 ]. However, there are few reports concerning the synthesis of selenium-based cyclic rings.…”

A general approach to construct selenopheno[3,2-b]indole-cored molecules using Fischer indolization

“…The family of selenium-containing heterocycles includes a wide range of various scaffolds, which are of great importance in the design of target molecules for both medicinal chemistry and materials science. [1][2][3][4][5][6][7] Among them, selenophenes, a class of fivemembered heteroaromatics with one atom of selenium, 8 have received significant attention from researchers across the globe due to their applications as pharmaceuticals, 9,10 photo-/electroactive materials 11,12 and intermediates for organic synthesis. 13,14 Therefore, selenophene-based molecules, including selenophene-fused architectures, are important targets of organic synthesis, and new effective methods for their construction and modification are highly in demand.…”

“…18 In turn, the construction of the selenopheno[3,2-b]indole (SeI) scaffold was readily performed via the intramolecular electrophilic cyclization of 3-alkylselanyl-2-ethynylindoles 5 by their treatment with I 2 to afford 2-aryl-or 2-alkyl-3-iodo-substituted SeI derivatives 6 as well as with FeCl 3 and dibutyl diselenide to afford 2-aryl-3butylselanyl-substituted SeI derivatives 7 (Scheme 1c). 19 In addition, four approaches for the construction of the benzo [4,5]selenopheno [3,2-b]indole (BSeI) core were also described in the literature, including Fischer indolization of benzo[b]selenophen-3(2H)-one arylhydrazones 8 by their treatment with HCl in glacial AcOH, 20,21 acid-promoted reaction of 2-(selenocyanato)acetophenones 9 with phenylhydrazine through the initial formation of 2-(2-selenocyanatophenyl) indoles and next their cyclization, 22 the Cadogan cyclization of compound 10 upon its treatment with P(OEt) 3 , 23 and Cu-catalyzed reaction of 2-(2-iodophenyl)indoles 11 with elemental Se via intramolecular C-Se bond formation 24 (Scheme 2).…”