Abstract The preparation of α, ω-diynes with methyl groups at the termini (11a-i) is described. The methylene groups between the alkyne units vary between n= 12 (a) and n= 4 (i). Ring closing metathesis with Mo (CO) 6/CF 3 C 6 H 4 OH yielded the monocyclic alkyne 12a with 11a as starting material, whereas 11b-g yielded the cyclic diynes 13b-g. Detailed structural parameters were obtained for 13b and 13c by X-ray crystallography.
