Synthesis of 1-Aryltetralins and 1-Arylnaphthalenes via (4 + 2) Annulation of β-Ketosulfones with Styryl Bromides.

A novel route has been developed for the synthesis of various substituted 1-aryltetralins 6 and 1-arylnaphthalenes 8 via (1) K2CO3-mediated α-styrylation of β-ketosulfones 3 with bromostyryl bromides 4 and (2) stereocontrolled NaBH4-promoted reduction of the resulting γ-alkenones 5, followed by BF3·OEt2-catalyzed intramolecular annulation of the corresponding γ-alkenols 7 under rt/5 h and reflux/10 h conditions, respectively. The key structures of 6 and 8 were confirmed by X-ray crystallographic analysis. A plausible mechanism has been proposed.