125615-96-5Relevant articles and documents
Regio-and stereocontrolled dimerization of tert-butylacetylene to (Z)-1,4-Di-tert-butylbutatriene by ruthenium catalysis. Reaction mechanism involving alkynyl-vinylidene coupling and rearrangement of the metal-bound C4 unit
Wakatsuki, Yasuo,Yamazaki, Hiroshi,Kumegawa, Nami,Satoh, Toshiaki,Satoh, James Y.
, p. 9604 - 9610 (2007/10/02)
Ruthenium complexes, Ru(cod)(cot) (cod = 1,5-cyclooctadiene, cot = cyclooctariene) and Ru(CO)(PPh3)3(H)2 (1), catalyze the dimerization of tert-butylacetylene to (Z)-1,4-di-tert-butylbutatriene ((Z)-dbb). In the case of the Ru(cod)(cot) catalyst, the addition of bulky tertiary phosphines is an essential factor to effect good selectivity to dbb, the byproducts being isomers of 1,3-enynes. From the reaction of 1 with tert-butylacetylene, Ru(CO)(PPh3)3(H)(C≡CtBu) was isolated, which reacted further with HC≡CtBu to give Ru(CO)(PPh3)3(C≡CtBu)2 (3). The halogen analogue of this complex RuX2(PPh3)3, reacted with HC≡CtBu to give vinylidene comPlexes RuX2(PPh3)2(C=CHtBu) (11a, X = Cl; 11b, X = Br). Reaction of 11a with a calculated amount of LiC≡CtBu followed by bubbling of CO yielded RuCl(CO)(PPh3)3{C(C≡CtBu)=CH tBu} (12) where the C≡CtBu group and tBu are mutually cis to each other with respect to the double bond of the C4 unit. Complex 12 in tenzene decomposed at 50°C releasing the C4 chain as (Z)-dbb. From these reactions, the mechanism for the catalytic production of (Z)-dbb has been derived. The X-ray structure of 12 is reported.
