Limits...
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.


Cooperative hydrogen atom transfer, or the sequential removal of hydrogen atoms from a substrate by two different catalysts, has been successfully applied to the acceptorless dehydrogenation of alkanes. We reasoned that this same approach could be applied to the dehydroformylation of aldehydes.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC5384452&req=5

fig5: Cooperative hydrogen atom transfer, or the sequential removal of hydrogen atoms from a substrate by two different catalysts, has been successfully applied to the acceptorless dehydrogenation of alkanes. We reasoned that this same approach could be applied to the dehydroformylation of aldehydes.

Mentions: We have recently developed a cooperative catalyst system that can dehydrogenate unfunctionalized organic compounds through successive hydrogen atom transfer (HAT) events to different catalysts; this method utilizes UV light to activate one of the HAT catalysts and is capable of generating alkenes from alkanes with dihydrogen as the sole by-product (Fig. 5).19 This system features tetrabutylammonium decatungstate (TBADT), a high-valent base metal photocatalyst, to perform an initial, high-energy HAT to generate a putative, reactive organic radical intermediate. This open shell species can then transfer its highly labilized20,21 second hydrogen atom to the second catalyst, cobaloxime pyridine chloride (COPC), a vitamin B12 model compound, generating the desired alkene and two reduced catalysts. These two reduced, hydrido-catalysts can then interact to liberate dihydrogen, closing the catalytic cycle. Combined with the knowledge that both catalysts can function in the presence of CO,22–24 we considered whether such a strategy might be applicable to dehydroformylation.


Toward a mild dehydroformylation using base-metal catalysis † † Electronic supplementary information (ESI) available. See DOI: 10.1039/c6sc04607j Click here for additional data file.
Cooperative hydrogen atom transfer, or the sequential removal of hydrogen atoms from a substrate by two different catalysts, has been successfully applied to the acceptorless dehydrogenation of alkanes. We reasoned that this same approach could be applied to the dehydroformylation of aldehydes.
© Copyright Policy - open-access
Related In: Results  -  Collection

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

fig5: Cooperative hydrogen atom transfer, or the sequential removal of hydrogen atoms from a substrate by two different catalysts, has been successfully applied to the acceptorless dehydrogenation of alkanes. We reasoned that this same approach could be applied to the dehydroformylation of aldehydes.
Mentions: We have recently developed a cooperative catalyst system that can dehydrogenate unfunctionalized organic compounds through successive hydrogen atom transfer (HAT) events to different catalysts; this method utilizes UV light to activate one of the HAT catalysts and is capable of generating alkenes from alkanes with dihydrogen as the sole by-product (Fig. 5).19 This system features tetrabutylammonium decatungstate (TBADT), a high-valent base metal photocatalyst, to perform an initial, high-energy HAT to generate a putative, reactive organic radical intermediate. This open shell species can then transfer its highly labilized20,21 second hydrogen atom to the second catalyst, cobaloxime pyridine chloride (COPC), a vitamin B12 model compound, generating the desired alkene and two reduced catalysts. These two reduced, hydrido-catalysts can then interact to liberate dihydrogen, closing the catalytic cycle. Combined with the knowledge that both catalysts can function in the presence of CO,22–24 we considered whether such a strategy might be applicable to dehydroformylation.

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.