A systematic study on the regioselective cyclization of benzene‐ and naphthalene‐based unsymmetrical diols with HBr (33 %) in acetic acid at room temperature led to the formation of annulation products. By using this method, synthesis of a wide variety of anthracene, tetracene and naphtho[b]thiophene analogues was achieved in good to excellent yields. By employing HBr (33 %) in acetic acid as a catalyst for regioselective cyclization of unsymmetrical diols was very facile and devoid of commonly encountered dihydroisobenzofuran formation.

A facile protocol for synthesis of naphth-annulated thiophenes has been developed via benzo-DMTHFs/triflic acid-mediated annulation of thiophenes. Furthermore, this methodology was found to be successful with substituted benzo-DMTHFs as well as higher homologues of benzo-DMTHF. tetraacetate, [16] ZnBr 2 /SiO 2 catalyzed annulation of electron-rich arenes with acetyl bromide-phthalaldehydes, [17a] Lewis acidinduced cyclization of aldehydes, [17b] A Lewis acid-mediated annulation of 2/3-(bromomethyl)indoles with arenes/heteroarenes, [18] palladium-catalyzed annulation of an in situ generated aryne annulation by o-halostyrene, [19] HI/P-mediated reductive [a] Dr.Figure 1. Synthesis of naphth-annulated arenes and heteroarenes.

Regioselective Annulation of Unsymmetrical 1,2-Phenylenebis(diaryl/diheteroarylmethanol): A Facile Synthesis of Anthracene, Tetracene, and Naphtho[b]thiophene Analogues. -(SIVASAKTHIKUMARAN, R.; RAFIQ, S. M.; SANKAR, E.; CLEMENT, J. A.; MOHANAKRISHNAN*, A. K.; Eur. J. Org. Chem. 2015, 35, 7816-7835, http://dx.doi.org/10.1002/ejoc.201501087 ; Dep. Org. Chem., Univ. Madras, Chennai 600 025, India; Eng.) -H. Hoennerscheid 15-034