C–O and C–S bond activation of allyl esters, ethers, and sulfides by low valent ruthenium complexes

Abstract

Allyl carboxylates or ethers react with Ru(cod)(cot) ( 1) [cod: 1,5-cyclooctadiene, cot: 1,3,5-cyclooctatriene] in the presence of monodentate tertiary phosphines such as PMe 3, PEt 3, PMe 2Ph or PMePh 2 to give a series of neutral (η 3-allyl)ruthenium(II) complexes Ru(η 3-C 3H 5)(OCOCF 3)(PR 3) 3 [PR 3=PEt 3 ( 2a), PMe 3 ( 2b), PMe 2Ph ( 2c), PMePh 2 ( 2d)], Ru(η 3-C 3H 5)(OCOR′)(PMe 3) 3 [R′=Me ( 2e), Ph ( 2f)], Ru(η 3- syn-C 3H 4R)(OCOCF 3)(PMe 3) 3 [R=Me ( 2g), Ph ( 2h)] and Ru(OAr)(η 3-C 3H 5)(PMe 3) 3 [Ar=Ph ( 3a), C 6H 4- o-Me ( 3b), C 6H 4- o-Et ( 3c), C 6H 4- o-OMe ( 3d)], whereas similar reactions of these allyl ethers, sulfides and carboxylates in the presence of the bidentate depe ligand [depe=1,2-bis(diethylphosphino)ethane] afford the cationic (η 3-allyl)ruthenium(II) complexes, [Ru(η 3-C 3H 5)(depe) 2] +[RY] − [RY=PhS ( 4a), MeS ( 4b), PhO ( 4c), CF 3COO ( 4d), CH 3COO ( 4e)]. Protonolysis of all (η 3-allyl)ruthenium(II) and (η 3-crotyl)ruthenium(II) complexes with HCl liberate propylene and trans-2-butene, respectively. Complex 2a reacts with benzaldehyde to give 1-phenyl-3-butene-1-ol. Reaction of 2b with CO forces the bonding mode of allyl moiety in 2a from η 3 to η 1.