For the creation of adaptable carbonyl compounds in organic synthesis, the oxidation of alcohols is a crucial step. As a sustainable alternative to the harmful traditional oxidation processes, ...transition-metal catalysts have recently attracted a lot of interest in acceptorless dehydrogenation reactions of alcohols. Here, using well-defined, air-stable palladium(II)-NHC catalysts (A-F), we demonstrate an effective method for the catalytic acceptorless dehydrogenation (CAD) reaction of secondary benzylic alcohols to produce the corresponding ketones and molecular hydrogen (H
). Catalytic acceptorless dehydrogenation (CAD) has been successfully used to convert a variety of alcohols, including electron-rich/electron-poor aromatic secondary alcohols, heteroaromatic secondary alcohols, and aliphatic cyclic alcohols, into their corresponding value-added ketones while only releasing molecular hydrogen as a byproduct.
Traditional cross‐coupling reactions show some disadvantages like the use of organohalides or the production of stoichiometric amounts of waste. The dehydrative homo‐ or heterocoupling of alcohols ...therefore arises as an interesting approach for a highly atom‐economical formation of carbon–carbon bonds, since water is produced as the only by‐product. We herein report a simple and direct, metal‐free protocol for the synthesis of olefins by applying catalytic amounts of a sulfonic acid and triphenylphosphane under air. A variety of olefins could be synthesized from benzylic alcohols under relatively mild conditions. Additionally, dehydrative hydroarylation of benzylic alcohols with electron‐rich arenes was possible by using only Brønsted acid under otherwise same reaction conditions. We could show that phosphane additives are essential to overcome oligomerization as main side reaction by the occupancy of the reactive carbocation intermediate.
A combination of Brønsted acid and Lewis base catalyses two dehydrative transformations of benzylic alcohols: homocoupling and hydroarylation.
Direct oxidation of primary alcohols to the corresponding carboxylic acids is performed highly efficiently at room temperature with anhydrous
tert-butyl hydroperoxide in the presence of a catalytic ...amount of CuCl under ligand free conditions in acetonitrile. Benzylic alcohols and allylic alcohols are more reactive than aliphatic alcohols, and are selectively oxidized to the corresponding acids in the presence of aliphatic alcohols such as 1-octanol and 1-decanol.
Direct oxidation of primary alcohols to the corresponding carboxylic acids is performed highly efficiently at room temperature with anhydrous
tert-butyl hydroperoxide in the presence of a catalytic amount of easily available CuCl under ligand free conditions in acetonitrile. Benzylic alcohols are more reactive than aliphatic alcohols, and these benzylic alcohols are selectively oxidized to the corresponding acids in the presence of aliphatic alcohols such as 1-octanol and 1-decanol.
In this review, we discussed about the synthetic developments in the field of Fe‐catalysis for the formation of ‐ bonds through the coupling of alkynes and alcohols, for the period of 13 years ...(2008‐2020). These strategies fulfil important Green Chemistry principles, as they are highly atom economic (up to 100 %), no toxic by‐products (only water), employs highly abundant and low toxic alcohols (no need for any pre‐functionalization hence step economy) and cheaper Fe‐catalysts. Having these advantages, one can predict that in the coming years a large number of fascinating new iron‐catalyzed reactions will be developed for the organic synthesis. We hope that this review article will be highly useful for the synthetic community to design and develop new Fe‐catalyzed coupling reactions and keeps the content in the right prospect.
The present review article deals with the synthetic developments in the field of Fe‐catalysis for the construction of C‐C bonds through the coupling of alkynes and alcohols particularly during the last 13 years (2008–2020). These strategies fulfil important Green Chemistry principles, as they are highly atom economic (up to 100 %), no toxic by‐products (only water), employs highly abundant and low toxic alcohols (no need for any pre‐functionalization hence step economy) and cheaper Fe‐catalysts. Having these advantages, one can predict the huge boost in the area of development of fascinating and new iron‐catalyzed reactions and their applications in organic synthesis
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An oxidovanadium(IV) complex having a perrhenato ligand VO(ReO4)(4,4′-tBubpy)20.25SO4·0.5ReO4 (4,4′-tBubpy=4,4′-di-tert-butyl-2,2′-bipyridine) efficiently catalyzes not only ...dehydrogenative oxidation of benzylic and propargylic mono-alcohols but also oxidative CC bond cleavage of meso-1,2-diaryl-1,2-ethanediols under atmospheric molecular oxygen, affording the corresponding carbonyl compounds in good yield.
We report a simple, yet efficient metal-free oxidation of secondary benzylic alcohols in the presence of t-butyl hydroperoxide (70% TBHP) with high yields of up to 98%. This type of reaction can be ...carried out using a wide variety of substrates, requires no other organic solvent, and proves to be tolerant toward a variety of different functional groups.
Celotno besedilo
Dostopno za:
BFBNIB, DOBA, GIS, IJS, IZUM, KILJ, KISLJ, NUK, PILJ, PNG, SAZU, UILJ, UKNU, UL, UM, UPUK
A self‐sufficient cytochrome P450 monooxygenase from Deinococcus apachensis (P450DA) was identified and successfully overexpressed in Escherichia coli BL21(DE3). P450DA would be a member of the ...CYP102D subfamily and assigned as CYP102D2 according to the phylogenetic tree and sequence alignment. Purification and characterization of the recombinant P450DA indicated both NADH and NADPH could be used by P450DA as a reducing cofactor. The recombinant E. coli (P450DA) strain was functionally active, showing excellent enantioselectivity for benzylic hydroxylation of methyl 2‐phenylacetate. Further substrate scope studies revealed that P450DA is able to catalyze benzylic hydroxylation of a variety of compounds, affording the corresponding chiral benzylic alcohols in 86–99 % ee and 130–1020 total turnover numbers.
A self‐sufficient cytochrome P450 monooxygenase from Deinococcus apachensis (P450DA) was identified and successfully overexpressed in Escherichia coli BL21(DE3). Further substrate scope studies revealed that P450DA is able to catalyze benzylic hydroxylation of a variety of compounds, affording the corresponding chiral benzylic alcohols in 86–99 % ee and 130–1020 total turnover numbers.
Abstract
The catalytic performance of Perfluorosulfonic acid resin (PFSA), a solid superacid, was studied in the catalytic benzylation of 1,3‐dicarbonyl compounds with benzylic alcohols. The ...PFSA‐catalyzed reactions could proceed smoothly to provide the products under solvent‐free conditions or in toluene and dichloromethane, which gave moderate to excellent yields. Due to its high chemical stability, PFSA was quite stable under the reaction conditions and could be recovered at least eight times without significant reduction of its catalytic effect. Moreover, this reaction was investigated at a 20 mmol scale, which indicated the potential applicability of the large‐scale industrial synthesis. Finally, the mechanism of the PFSA‐catalyzed benzylation of 1,3‐dicarbonyl compounds with benzylic alcohols was also investigated.
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A novel convenient two-stage synthesis of aryltetraline lignin analogues from aromatic aldehydes and diallyl diboron derivatives on the basis of intramolecular Friedel–Crafts reaction ...has been developed.
The synthesis of primary, secondary, and tertiary alcohols by the 1,2‐addition of arylboronic acids or boronates to carbonyl compounds, including unactivated ketones, using novel bulky yet flexible ...N‐heterocyclic carbene (NHC)‐coordinated 2,6‐di(pentan‐3‐yl)aniline (IPent)‐based cyclometallated palladium complexes (CYPs) as catalysts is reported. The PhS‐IPent‐CYP‐catalyzed reactions are efficient at low catalyst loadings (0.02–0.3 mol% Pd), and the exceptional catalytic activity for 1,2‐addition is attributed to the steric bulk of the NHC ligand. These reactions can yield a wide range of functionalized benzylic alcohols that are difficult to synthesize by classical protocols using highly active organomagnesium or lithium reagents.
Organopalladium catalysis: The N‐heterocyclic carbene (NHC)‐coordinated IPent‐based cyclometallated palladium complexes (IPent‐CYPs) was synthesized and used as the catalyst for the 1,2‐addition of arylboron compounds to various carbonyl compounds including unactivated ketones. Bulky yet flexible IPent‐CYPs had excellent catalytic performance in this reaction, far superior to that of bulky and less flexible IPr*‐CYP.
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