AbstractSix bis(silyl)acetylenes (XMe2SiCCSiMe2X) with the following varied silicon substituents X were prepared: 1 (Me, Me); 2 (H, H); 3 (C1, H); 4 (CI, CI); 5 (MeO, H); 6 (MeO, MeO). While 1 and 2 may be prepared by the reaction of dilithio‐ or bis(bromomagnesium)‐acetylide with the appropriate chlorosilane, similar reactions designed to give 3–6 yielded oligomers, XMe2Si(CCSiMe2)nX, 7, X=CI, MeO, as the major products, indicating that the acetylenic functionality on silicon activates the chlorosilane towards nucleophilic substitution. Compounds 3 and 4 were prepared by free radical chlorination of 2. Methanolysis of 3 and 4 gave quantitative yields of 5 and 6 respectively.Compounds 1–6 undergo a Diels–Alder reaction with α‐pyrone to produce, after loss of carbon dioxide, bis(silyl)‐substituted benzene derivatives. The order of reactivity has been determined to be: 4=6>3=5>1>2, indicating that chloro or alkoxy substituents favor the cycloaddition with 2‐ pyrone. The adducts formed by compounds 3–6 undergo an unusually facile hydrolysis or elimination to give 1,1,3,3‐tetramethyl‐1,3‐disila‐2‐oxaindane.