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Toward a mild dehydroformylation using base-metal catalysis † † Electronic supplementary information (ESI) available. See DOI: 10.1039/c6sc04607j Click here for additional data file.

View Article: PubMed Central - PubMed

ABSTRACT

Dehydroformylation, or the reaction of aldehydes to produce alkenes, hydrogen gas, and carbon monoxide, is a powerful transformation that is underdeveloped despite the high industrial importance of the reverse reaction, hydroformylation. Interestingly, nature routinely performs a related transformation, oxidative dehydroformylation, in the biosynthesis of cholesterol and related sterols under mild conditions using base-metal catalysts. In contrast, chemists have recently developed a non-oxidative dehydroformylation method; however, it requires high temperatures and a precious-metal catalyst. Careful study of both approaches has informed our efforts to design a base-metal catalyzed, mild dehydroformylation method that incorporates benefits from each while avoiding several of their respective disadvantages. Importantly, we show that cooperative base metal catalysis presents a powerful, mechanistically unique approach to reactions which are difficult to achieve using conventional catalyst design.

No MeSH data available.


The addition of stoichiometric TEMPO significantly impedes reaction progress.
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fig7: The addition of stoichiometric TEMPO significantly impedes reaction progress.

Mentions: Although the mild dehydroformylations described herein are consistent with the cooperative HAT process outlined in Fig. 5, we sought to gain additional insight into its operative mechanism. Subjecting the reaction of 3a to a stoichiometric quantity of the radical inhibitor 2,2,6,6-tetramethylpiperidine 1-oxyl (TEMPO) significantly impeded the reaction (Fig. 7), a result consistent with the intermediacy of free radicals (though radical trap experiments should be interpreted with care37). This information, combined with the spectroscopic data described in our dehydrogenation study19 provide a collective body of evidence that supports a reaction mechanism featuring an irreversible loss of two gases and two catalyst-dependent hydrogen atom transfer steps.


Toward a mild dehydroformylation using base-metal catalysis † † Electronic supplementary information (ESI) available. See DOI: 10.1039/c6sc04607j Click here for additional data file.
The addition of stoichiometric TEMPO significantly impedes reaction progress.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC5384452&req=5

fig7: The addition of stoichiometric TEMPO significantly impedes reaction progress.
Mentions: Although the mild dehydroformylations described herein are consistent with the cooperative HAT process outlined in Fig. 5, we sought to gain additional insight into its operative mechanism. Subjecting the reaction of 3a to a stoichiometric quantity of the radical inhibitor 2,2,6,6-tetramethylpiperidine 1-oxyl (TEMPO) significantly impeded the reaction (Fig. 7), a result consistent with the intermediacy of free radicals (though radical trap experiments should be interpreted with care37). This information, combined with the spectroscopic data described in our dehydrogenation study19 provide a collective body of evidence that supports a reaction mechanism featuring an irreversible loss of two gases and two catalyst-dependent hydrogen atom transfer steps.

View Article: PubMed Central - PubMed

ABSTRACT

Dehydroformylation, or the reaction of aldehydes to produce alkenes, hydrogen gas, and carbon monoxide, is a powerful transformation that is underdeveloped despite the high industrial importance of the reverse reaction, hydroformylation. Interestingly, nature routinely performs a related transformation, oxidative dehydroformylation, in the biosynthesis of cholesterol and related sterols under mild conditions using base-metal catalysts. In contrast, chemists have recently developed a non-oxidative dehydroformylation method; however, it requires high temperatures and a precious-metal catalyst. Careful study of both approaches has informed our efforts to design a base-metal catalyzed, mild dehydroformylation method that incorporates benefits from each while avoiding several of their respective disadvantages. Importantly, we show that cooperative base metal catalysis presents a powerful, mechanistically unique approach to reactions which are difficult to achieve using conventional catalyst design.

No MeSH data available.