1190481-97-0Relevant articles and documents
Synthesis and structural characterization of a series of new chiral-at-metal ruthenium allenylidene complexes
Costin, Stephen,Widaman, Andria K.,Rath, Nigam P.,Bauer, Eike B.
, p. 1269 - 1282 (2011/06/09)
New chiral-at-metal ruthenium indenyl PPh3 phosphoramidite allenylidene complexes have been synthesized and structurally characterized. Through thermal ligand-exchange reactions with [RuCl(Ind)(PPh3) 2], the phosphoramidite ligands (R)-binol-N,N-dimethylphosphoramidite (5a), (R)-binol-N,N-dibenzylphosphoramidite (5b), (R,S)-binol-N-benzyl-N- α-methylbenzylphosphoramidite (5c), and (R)-catechol-2- methylpyrrolidinephosphoramidite [(R)-10] were converted into the complexes [RuCl(Ind)(PPh3)(L)] [L = 5a, 79%; 5b, 87%; 5c, 80%, (R)-10, 67%]. The complexes [RuCl(Ind)(PPh3)(5b)] and [RuCl(Ind)(PPh 3)(5c)] were obtained diastereomerically pure and, by reaction with propargylic alcohols, subsequently converted into the allenylidene complexes [Ru(Ind)(PPh3)(5b)(=C=C=CRR′)]+ PF6 - (R = R′ = Ph, 85%; R = Ph, R′ = Me, 66%; R = 2-furyl, R′ = Me, 94%; R = R′ = 4-fluorophenyl, 76%; R = 4-methoxyphenyl, R′ = Me, 66%) and [Ru(Ind)(PPh3)(5c)(=C=C=CRR′)] + PF6- (R = R′ = Ph, 91%; R = Ph, R′ = Me, 72%; R = 2-furyl, R′ = Me, 93%), which were also obtained diastereomerically pure. Complex [RuCl(Ind)(PPh3)(5b)] and three of the new allenylidene complexes were characterized structurally, which showed that the chiral information was transferred from the precursor complex to the corresponding allenylidenes. Dynamic NMR experiments showed that during the synthesis of allenylidene complexes only one diastereomer was formed. The research presented herein has an impact on the chemistry of chiral allenylidene complexes as catalysts and as potential intermediates in propargylic substitution reactions. Chiral-at-metal ruthenium chloro indenyl phosphoramidite complexes have been converted into the corresponding allenylidene complexes, some of which have been structurally characterized. The chiral information was transferred from the chloro precursor complexes to the allenylidene complexes, which were obtained as optically pure diastereomers. Only one diastereomer was formed during the syntheses. Copyright
