Reactions of naphtho[b]cyclopropene with trithiocarbonyl derivatives in chloroform afforded 1,3-dihydrobenzo[2,3-c]thiophenederivatives in moderate yields through a [2π+2σ] type cycloaddition process. The similar reaction with a dithiocarbonate compound gave a recovery of the starting material. A reaction with thiotropone resulted in a [8π+2σ] type adduct in 5% yield. Solvent effects on the product