Aerobic carbon-carbon bond cleavage of alkenes to aldehydes catalyzed by first-row transition-metal-substituted polyoxometalates in the presence of nitrogen dioxide

Amir Rubinstein, Pablo Jiménez-Lozanao, Jorge J. Carbó, Josep M. Poblet, Ronny Neumann*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

81 Scopus citations

Abstract

A new aerobic carbon-carbon bond cleavage reaction of linear di-substituted alkenes, to yield the corresponding aldehydes/ketones in high selectivity under mild reaction conditions, is described using copper(II)-substituted polyoxometalates, such as {α2-Cu(L)P2W 17O61}8- or {[(Cu(L)]2WZn(ZnW 9O34)2}12-, as catalysts, where L = NO2. A biorenewable-based substrate, methyl oleate, gave methyl 8-formyloctanoate and nonanal in >90% yield. Interestingly, cylcoalkenes yield the corresponding epoxides as products. These catalysts either can be prepared by pretreatment of the aqua-coordinated polyoxometalates (L = H 2O) with NO2 or are formed in situ when the reactions are carried with nitroalkanes (for example, nitroethane) as solvents or cosolvents. Nitroethane was shown to release NO2 under reaction conditions. 31P NMR shows that the Cu-NO2-substituted polyoxometalates act as oxygen donors to the C-C double bond, yielding a Cu-NO product that is reoxidized to Cu-NO2 under reaction conditions to complete a catalytic cycle. Stoichiometric reactions and kinetic measurements using {α2-Co(NO2)P2W17O 61}8- as oxidant and trans-stilbene derivatives as substrates point toward a reaction mechanism for C-C bond cleavage involving two molecules of {α2-Co(NO2)P2W 17O61}8- and one molecule of trans-stilbene that is sufficiently stable at room temperature to be observed by 31P NMR.

Original languageEnglish
Pages (from-to)10941-10948
Number of pages8
JournalJournal of the American Chemical Society
Volume136
Issue number31
DOIs
StatePublished - 6 Aug 2014
Externally publishedYes

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