Nosyl (2-Nitrobenzenesulfonyl) Annulation Strategy toward Winding Vine-Shaped Bithiophenes

Winding vine-shaped bithiophene was
synthesized through the nosyl
(2-nitrobenzenesulfonyl) cyclization protocol. The reaction of bithiophene
bearing bromomethyl groups at the 3,3′-positions with nosylated
1,2-ethylenediamine in the presence of potassium carbonate afforded
the annulated product in excellent yield. The obtained bithiophene
was found to contain a 10-membered ring, which was confirmed by X-ray
analysis. The related nosyldiamine bearing a tri- or tetramethylene
group also reacted in a similar manner, affording an 11- or 12-membered
macrocycle, respectively.