Sesquiterpenes have been a rich source of bioactive compounds and have inspired innovative methodological developments. Herein we report a rapid and scalable synthesis of a substrate for a 4+3 cycloaddition in order to access the cis-fused bicyclic system of the guaianes. We further show diverse and efficient functionalizations of the bicyclic system. The relative stereochemistry was assigned based on the crystal structure of a key product.