A facile two-step synthesis of thiophene end-capped aromatic systems

Synthesis of Annulated Thiophenes Involving Benzo‐DMTHFs/Triflic acid‐Mediated Domino Reactions

“…Under identical conditions, naphth‐annulation of 2‐methyl thiophene 10 a afforded isomeric naphtho[ b ]thiophenes 11 a and 11 a′ . Next, the domino reaction of naphtho[2,3‐ b ]thiophene 10 b with benzo‐DMTHF 2 led to the isolation of annulated thiophenes 11 b and 11 b′ (Scheme ). The structures of these heterocycles 11 b and 11 b′ are assigned based on the literature reports…”

Synthesis and Characterization of New Helical Coumarins

“…A solution of 1‐methyl‐9‐hydroxy‐naphtho[2,1‐ b ]pyranone 9 (0.300 g, 1.42 mmol), 2‐mercaptoethanol (0.600 mL, 8.56 mmol), and trifluoromethane sulfonic acid (0.315 mL, 3.56 mmol) in chlorobenzene was refluxed for 24 h . After completion of the reaction, the mass was poured on ice/water and extracted with ethyl acetate (2 × 50 mL), and then the organic layer was washed with NaOH solution (10%) and water, dried over sodium sulfate, and concentrated under reduced pressure to obtain the crude pale yellow solid.…”

“…However, these two substituents may not show sufficient crowding for a stable and pronounced helical structure at the ambient conditions. The hydroxyl group of 2‐naphthol, or similar systems, has been directly converted to thiophene or dihydrothiophene by an acid‐catalyzed reaction with 2‐mercaptoethanol . Because we are interested to build a suitable 1,8‐ peri interaction, the intermediate 12 was subjected to the same condition, and two products were isolated.…”

A Simple, Serendipitous Synthesis of Heterohexahelicenes

“…Benzo[1,2‐ b :3,4‐ b ′‐5,6‐ b ′′]trithiophene ( 1 or C 3 h ‐BTT, Scheme ), is trivially prepared from phloroglucinol in two steps . This and the six other isomers of benzotrithiophene are calculated to be excellent electron donors, and we have prepared a variety of charge transfer complexes by the crystallization of 1 with organic acceptors .…”