RT info:eu-repo/semantics/article
T1 A Radical Mechanism for the Vanadium-Catalyzed Deoxydehydration of Glycols
A1 Vicente Poutás, Luis Carlos de
A1 Castiñeira Reis, Marta
A1 Sanz Díez, Roberto
A1 Silva López, Carlos
A1 Nieto Faza, Olalla .
K1 Chemistry, Organic
K1 Química orgánica
AB We propose a novel mechanism for the deoxydehydration (DODH) reaction of glycols catalyzed by a [Bu4N][VO2(dipic)] complex (dipic = pyridine-2,6-dicarboxylate) using triphenylphosphine as a reducing agent. Using density functional theory, we have confirmed that the preferred sequence of reaction steps involves reduction of the V(V) complex by phosphine, followed by condensation of the glycol into a [VO(dipic)(-O-CH2CH2-O-)] V(III) complex (6), which then evolves to the alkene product, with recovery of the catalyst. In contrast to the usually invoked closed-shell mechanism for the latter steps, where 6 suffers a [3+2] retrocycloaddition, we have found that the homolytic cleavage of one of the C–O bonds in 6 is preferred by 12 kcal/mol. The resulting diradical intermediate then collapses to a metallacycle that evolves to the product through an aromatic [2+2] retrocycloaddition. We use this key change in the mechanism to propose ways to design better catalysts for this transformation. The analysis of the mechanisms in both singlet and triplet potential energy surfaces, together with the location of the MECPs between them, showcases this reaction as an interesting example of two-state reactivity.
PB American Chemical Society
SN 0020-1669
YR 2016
FD 2016-11
LK http://hdl.handle.net/10259/4273
UL http://hdl.handle.net/10259/4273
LA eng
NO Xunta de Galicia and Ministerio de Economiá yCompetitividad for funding through Projects EM2014/040and CTQ2013-48937-C2-1-P and CTQ2013-48937-C2-2-P,respectively. R.S. thanks the Junta de Castilla y León forfunding through projects BU237U13 and BU076U16.
DS Repositorio Institucional de la Universidad de Burgos
RD 23-nov-2024