Addition of alkynes to coordinated allyl ether in ruthenium(II) chelate complexes

Reactions of the ruthenium chelate complex [Ru(eta(5):eta(2)-C5Me4CH2OCH2CH =CH2)(CO)Cl] (1) with acetylenes (RC)-C-1=CR2 in the presence of AgBF4 give the cationic diene chelates [Ru(eta(5):eta(4)-C5Me4CH2OCH2CH=CHCR1=CHR2)(C O)]+BF4- (2a, R-1 = R-2 = Ph; 3a, R-1 = R-2 = Me; 4a, R-1 = Me, R-2 = Ph; 4 b, R-1 = Ph, R-2 = Me; 5a, R-1 = H, R-2 = CO2Me; 5b, R-1 = CO2Me, R-2 = H; 6a, R-1 = H, R-2 = CH2OMe) and {Ru[eta(5):eta(4)-C5Me4CH2OCH2C(=CH2)CH=CHPh ](CO)}(+)-BF4- (7). The crystal structures of [2a "]+PF6- and [7]+PF6- have been determined. The formation of complexes 2-6 is the result of regiospec ific addition of acetylenes PhC=CMe, MeC=CMe, PhC=CMe, HC=CCO2Me, and HC=CC H2OMe to the terminal carbon of the allylic ether, while phenylacetylene ad ds to the internal carbon of the olefin. The unsymmetric acetylenes (PhC=CM e, HC=CCO2Me) give predominantly the isomers 4a and 5a, where the allylic C -H has added to the acetylenic carbon bearing the less bulky substituent. T he complex [Ru(eta(5):eta(2)-Me4C5CH2OCH2CH=CH2)(eta(1)-C=CPh)(CO)] (8) was synthesized by the reaction of 1 with PhC=CLi in THF; the protonation of 8 with Et2O . HBF4 gave 7.