Defunctionalization has a direct impact on the synthesis of value added products (
e.g.
biomass degradation). In synthetic chemistry it enables the functional group to act as a transient directing ...group. In this mini review, we have described the chronological development of metal assisted defunctionalization reactions from the stoichiometric to the catalytic stage with their application in synthetic organic chemistry. The proposed catalytic cycles of the transformations have been described to make this review comprehensible.
The chronological development of metal assisted defunctionalization reactions is discussed from the stoichiometric to the catalytic stage with their application in synthetic organic chemistry.
A nitrile-based template attached with a phenylacetic acid framework promoted meta-selective C–H bond olefination. This palladium-catalyzed protocol is applicable to a wide range of substituted ...phenylacetic acids and tolerates a variety of functional groups. The versatility of this operationally simple method has been demonstrated through drug diversification.
Various practical methods for the selective C−H functionalization of the ortho and recently also of the meta position of an arene have already been developed. Following our recent development of the ...directing‐group‐assisted para C−H functionalization of toluene derivatives, we herein report the first remote para C−H functionalization of phenol derivatives by using a recyclable silicon‐containing biphenyl‐based template. The effectiveness of this strategy was illustrated with different synthetic elaborations and by the synthesis of various phenol‐based natural products.
The template‐assisted para C−H olefination of phenol derivatives was enabled by a silicon‐containing directing group (DG; see scheme) in combination with a palladium catalyst. This method was also applied to the synthesis of different natural products.
Site-selective C–H functionalization has emerged as an efficient tool in simplifying the synthesis of complex molecules. Most often, directing group (DG)-assisted metallacycle formation serves as an ...efficient strategy to ensure promising regioselectivity. A wide variety of ortho- and meta-C–H functionalizations stand as examples in this regard. Yet despite this significant progress, DG-assisted selective para-C–H functionalization in arenes has remained unexplored, mainly because it involves the formation of a geometrically constrained metallacyclic transition state. Here we report an easily recyclable, novel Si-containing biphenyl-based template that directs efficient functionalization of the distal p-C–H bond of toluene by forming a D-shaped assembly. This DG allows the required flexibility to support the formation of an oversized pre-transition state. By overcoming electronic and steric bias, para-olefination and acetoxylation were successfully performed while undermining o- and m-C–H activation. The applicability of this D-shaped biphenyl template-based strategy is demonstrated by synthesizing various complex molecules.
This discovery illustrates selective meta C-H bond activation from multiple non-equivalent C-H bonds present in medicinally relevant arylethanesulfonic acid and the 2-arylpropanoic acid moiety using ...weakly coordinating nitrile as a directing group. Transformation of the meta olefinated compounds to important organic molecules has been demonstrated. Efforts were made to obtain mechanistic detail of the meta C-H bond functionalization reaction.
A number of pharmaceutical compounds possess an arylated 2-pyridone moiety. The existing reports using expensive starting materials and/or superstoichiometric metal salts have prompted us to explore ...a possible user-friendly method for their synthesis. In this report, we demonstrate an easy-to-handle reaction condition with an iron catalyst for the exclusive generation of C-3-arylated pyridone via C–H functionalization.
Substoichiometric iron mediates the thioetherification of unactivated aliphatic C–H bonds directed by resident silylperoxides. Upon exposure to a catalytic amount of iron(II) triflate, ...TIPS-protected peroxides bearing primary, secondary, and tertiary C–H sites undergo chemoselective thioetherification of remote C–H bonds with diaryl disulfides. The reaction demonstrates a broad substrate scope and functional group tolerance without the use of any noble metal additives. Mechanistic experiments suggest that the reaction proceeds through 1,5-H atom abstraction by a hydroxyl radical generated with iron.
Transition metal‐catalyzed decarbonylation is an essential paradigm of synthetic organic chemistry. Decarbonylation offers a unique pathway to decoding the skeletal structure of arenes and enabling ...easy synthesis of structurally complicated molecules. Due to the omnipresence of carbonyl groups in a wide array of synthetically important complex molecules, the variety and scope of these transformations are enormous. As a result, the development of transition metal catalysts in such a simple decarbonylation reaction ranks among one of the most important topics in synthetic organic chemistry. Transition metals that have been employed range from 3d metals like V to second‐row transition metals like Pd. The growing potential of this methodology has driven the pioneers of synthetic organic chemistry into delving into the details of this transition metal‐catalyzed decarbonylation pathways. This review aims to take the readers through the employment of transition metals in various decarbonylation processes developed by our group, sticking not only to the scope and diversification of synthetically complex molecules, but also enabling the readers to understand the mechanistic insights, through computational and kinetic studies put forward in such reaction protocol, hoping to pave the way for future organic chemists to delve and hopefully solve the unique problems associated with this protocol.
The growing potential of decarbonylation methodology has driven the pioneers of synthetic organic chemistry into delving into the details of this transition metal‐catalyzed decarbonylation pathways. This review aims to take the readers through the employment of transition metals in various decarbonylation processes developed by our group, sticking not only to the scope and diversification of synthetically complex molecules, but also enabling the readers to understand the mechanistic insights, through computational and kinetic studies put forward in such reaction protocol.
An intramolecular dehydrogenative (sp3)C–O bond formation in salicylamides can be initiated by an active Cu/O2 species to generate pharamaceutically relevant dihydro-oxazinones. Experimental ...findings suggest that stereoelectronic parameters in both coupling partners are controlling factors for site selectivity in bond formation. Mechanistic investigations including isotope labeling, kinetic studies helped to propose a catalytic cycle. The method provides a convenient synthesis of an investigational new medicine CX-614, which has potential in finding treatment for Parkinson’s and Alzheimer’s diseases.
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