Dibenzoselenophene aromaticity

By far the most common methods for the preparation of dibenzoselenophenes and 2-benzoselenophenes, like the synthesis of 1-benzoselenophenes, rely upon the annulation of the heterocyclic ring system onto a preformed benzene ring and mostly involve the formation of one or two Se-C bonds as their key steps, with only a few exceptions [1, 119, 120], Intramolecular electrophilic aromatic substitution of biphenyl-2-yl trifluoromethylselenide to 5-(trifluoromethyl)dibenzoselenopheni um triflate (62) [99, 143] and synthesis of tetramethoxydibenzoselenophene (95) (Scheme 26) [144, 145] are examples. 

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