title: Mechanism of the rhodium-catalyzed asymmetric isomerization of allylamines to enamines.
abstract: A theoretical study of the mechanism of the rhodium-catalyzed asymmetric isomerization of allylamines to enamines by using density functional theory with the B3LYP functional leads us to discard the so far accepted nitrogen-triggered mechanism, in which the isomerization occurs on N-bonded intermediates and transition states, in favor of a variation of the classical allylic mechanism for olefin isomerization. The modified allylic mechanism consists of four main steps: 1) N-coordination of the allylamine to Rh(I); 2) intramolecular isomerization from kappa(1)-(N)-coordination to eta(2)-(C,C)-coordination of the allylamine; 3) oxidative addition of C(1)--H to form a distorted octahedral eta(3)-allyl complex of Rh(III); and 4) hydrogen transfer to C(3) (reductive C(3)--H elimination). The two hydrogen transfer steps (oxidative addition and reductive elimination) have the highest barriers of the overall process. The oxidative addition barrier, which includes solvent effects, is 28.4 kcal mol(-1). For the reductive elimination, the value in solvent is 28.6 kcal mol(-1), very similar to the oxidative addition barrier.
authors.affiliation: Unitat de Química Física, Edifici C.n. Universitat Autònoma de Barcelona, Bellaterra, Catalonia, Spain.
authors.forename: Ainara
authors.initials: A
authors.lastname: Nova
authors.forename: Gregori
authors.initials: G
authors.lastname: Ujaque
authors.forename: Ana C
authors.initials: AC
authors.lastname: Albéniz
authors.forename: Pablo
authors.initials: P
authors.lastname: Espinet