Transannular Diels–Alder reactions of 14-membered macrocyclic trienes possessing a methyl substituent on both the diene and dienophile moiety have been investigated. Macrocyclic structures 1a, 1b, and 1c having cis-trans-trans (CTT), trans-cis-trans (TCT), and trans-trans-trans (TTT) geometries could be stereoselectively constructed by coupling appropriately functionalized dienes 5 and dienophile 4 following an intramolecular displacement of an allylic halide by the anion of an appropriately located dimethyl malonate unit. The transannular Diels–Alder reaction performed on 1a led to a mixture of four major tricyclic products, including 34 possessing the unexpected trans-anti-cis (TAC) stereochemistry. When heated at 300 °C, macrocycle 1b underwent an unique conversion via an ene–retroene, Diels–Alder process, producing the unexpected tricycle 41 (racemic form) containing five contiguous chiral centers. A rationale for the above experimental facts is presented. In contrast to the previous results, the transannular Diels–Alder reaction of macrocycle 1c was straightforward, producing a 95% isolated yield of trans-anti-cis (TAC) tricycle 34. This investigation demonstrates a general methodology for the stereocontrolled synthesis of 1,2-dimethyl A.B.C[6.6.6] tricyclic compounds, which are potential precursors to polycyclic natural products such as steroids and terpenes.