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Addition of Alkynes to Coordinated Allyl Ether in Ruthenium(II) Chelate Complexes

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journal contribution
posted on 13.11.1999, 00:00 by Oleg V. Gusev, Alexander M. Kal'sin, Larisa N. Morozova, Pavel V. Petrovskii, Konstantin A. Lyssenko, Oleg L. Tok, Alfred F. Noels, Shane R. O'Leary, Peter M. Maitlis
Reactions of the ruthenium chelate complex [Ru(η52-C5Me4CH2OCH2CHCH2)(CO)Cl] (1) with acetylenes R1C⋮CR2 in the presence of AgBF4 give the cationic diene chelates [Ru(η54-C5Me4CH2OCH2CHCHCR1CHR2)(CO)]+BF4- (2a, R1 = R2 = Ph; 3a, R1 = R2 = Me; 4a, R1 = Me, R2 = Ph; 4b, R1 = Ph, R2 = Me; 5a, R1 = H, R2 = CO2Me; 5b, R1 = CO2Me, R2 = H; 6a, R1 = H, R2 = CH2OMe) and {Ru[η54-C5Me4CH2OCH2C(CH2)CHCHPh](CO)}+BF4- (7). The crystal structures of [2a‘ ‘]+PF6- and [7]+PF6- have been determined. The formation of complexes 26 is the result of regiospecific addition of acetylenes PhC⋮CMe, MeC⋮CMe, PhC⋮CMe, HC⋮CCO2Me, and HC⋮CCH2OMe to the terminal carbon of the allylic ether, while phenylacetylene adds to the internal carbon of the olefin. The unsymmetric acetylenes (PhC⋮CMe, 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. The complex [Ru(η52-Me4C5CH2OCH2CHCH2)(η1-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.