Hirano, M; Sakate, Y; Komine, N; Komiya, S; Wang, Xqi; Bennett, MA
Treatment of [Ru(eta(6)-C10H18)(eta(4)-1,5-COD)] (1) with excess butadiene at room temperature produces supine,prone-[Ru(eta(3):eta(3)-2,6-octadiene-1,8-diy1)(eta(4)-1,5-COD)] (supine,prone-2). Similar treatment of 1 with isoprene and (E)- and (Z)-1,3-pentadiene also gives the corresponding analogues of supine,protte-2, while 2,3-dimethylbutadiene does not react. A low-temperature NM R study of the reaction of 1 with butadiene shows initial formation of [Ru(eta(4)-cisoid-butadiene)(eta(2)-transoidbutadiene)(eta(4)-1,5-COD)] (5) as an intermediate, which is spontaneously converted into supine, prone-2 upon warming to room temperature. Similarly, treatment of 1 with (E)- 1,3-pentadiene gives two intermediates, [Ru {eta(4)-(E)-cisoid- 1,3-pent ad iene} {eta(2)-(E)-iransoid- 1,3-pen tad iene} (eta(4)- 1,5-COD)] (E-6) and [Ru{eta(4)-(Z)-cisoid-1,3-pentadiene}{eta(2)-(E)-transoid-1,3-pentadiene 1(eta(4)- 1,5-COD)] (Z-6), in 44/56 ratio at -50 degrees C. These intermediates are converted into unti-supine,syn-prone-[Ru-(eta(3):eta(3)-3,7-decadiene-2,9-diyl)(eta(4)-1,5-COD)] (anti-supine,syn-prone-4). The observed stereochemistries can be explained by a mechanism that involves oxidative coupling between eta(4)-(Z)-cisoid-1,3-pentadiene and eta(2)-(E)-transoid-1,3-pentadiene in Z-6.