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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.

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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 acceptorless dehydroxymethylation of primary alcohols, a hitherto-unknown chemical reaction, is possible using cooperative catalysis.
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fig8: The acceptorless dehydroxymethylation of primary alcohols, a hitherto-unknown chemical reaction, is possible using cooperative catalysis.

Mentions: Finally, in our initial report, we also showed the capability of this dual catalytic system to perform dehydrogenations of alcohols to ketones.19 Leveraging this observation, we wondered whether the dehydroxymethylation transformation, as performed enzymatically, might be possible using this catalyst system (Fig. 4). Subjecting dimethyl phenyl propanol 15 to the optimized dehydroformylation conditions resulted in both dimethyl phenyl propanal (3a), along with the dehydroxymethylation olefin products (3b/3c), in a 1.7 : 6:1 ratio (Fig. 8), showing that such a bio-inspired, tandem dehydrogenation/dehydroformylation reaction is possible using cooperative catalysis. The presence of both the intermediate aldehyde, and an olefin ratio consistent with the relevant dehydroformylation reaction above (Table 2, entry 2), suggests to us that the alcohol is proceeding through an oxidation/dehydroformylation sequence, conceptually similar to the enzymatic strategy outlined in Fig. 4 though mechanistically distinct. Although reductive dehydroxymethylation (that is, replacing –CH2OH with –H) has been described on multiple occasions in the literature,38–40 to our knowledge this represents the first loss of a hydroxymethyl group coupled with olefin formation in a non-enzymatic transformation.


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 acceptorless dehydroxymethylation of primary alcohols, a hitherto-unknown chemical reaction, is possible using cooperative catalysis.
© Copyright Policy - open-access
Related In: Results  -  Collection

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

fig8: The acceptorless dehydroxymethylation of primary alcohols, a hitherto-unknown chemical reaction, is possible using cooperative catalysis.
Mentions: Finally, in our initial report, we also showed the capability of this dual catalytic system to perform dehydrogenations of alcohols to ketones.19 Leveraging this observation, we wondered whether the dehydroxymethylation transformation, as performed enzymatically, might be possible using this catalyst system (Fig. 4). Subjecting dimethyl phenyl propanol 15 to the optimized dehydroformylation conditions resulted in both dimethyl phenyl propanal (3a), along with the dehydroxymethylation olefin products (3b/3c), in a 1.7 : 6:1 ratio (Fig. 8), showing that such a bio-inspired, tandem dehydrogenation/dehydroformylation reaction is possible using cooperative catalysis. The presence of both the intermediate aldehyde, and an olefin ratio consistent with the relevant dehydroformylation reaction above (Table 2, entry 2), suggests to us that the alcohol is proceeding through an oxidation/dehydroformylation sequence, conceptually similar to the enzymatic strategy outlined in Fig. 4 though mechanistically distinct. Although reductive dehydroxymethylation (that is, replacing –CH2OH with –H) has been described on multiple occasions in the literature,38–40 to our knowledge this represents the first loss of a hydroxymethyl group coupled with olefin formation in a non-enzymatic transformation.

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.