A tandem Prins/Friedel-Crafts cascade strategy has been developed for the synthesis of hexahydro-2Hbenzo[g]chromene derivatives. Under action of equimolecular amount of BF 3 etherate, δ,ε-unsaturated alcohols and arylacetaldehydes are coupled to form oxocarbenium ion intermediates, which are captured by the alkene moiety through a favored six-membered transition state. The Prins-cyclization resultant tertiary carbenium ions undergo consecutive intra-molecular Friedel-Crafts cyclization to create the tricyclic products. This process enables a tandem formation of three new chemical bonds in one single operation with high yields and stereoselectivity in most cases. When cyclic substituents are involved, a variety of spiro derivatives could also be synthesized successfully, which further proved the robustness of this methodology.