A catalytic domino spirocyclization of 1,7-enynes with simple cycloalkanes and cyclo-1,3-dicarbonyls has been established via multiple C–C bond formations from alkynyl/alkenyl functions and dual ...α,α-C(sp3)-H abstraction/insertion. The reaction involves addition, 6-exo-dig cyclization and radical coupling sequences under convenient catalytic conditions and provides a concise access to spiro cyclopentacquinolines in good to excellent yields.
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IJS, KILJ, NUK, PNG, UL, UM
While the hydrogen atom ion (HAA) from C(sp3)−H bond has been well explored, the radical‐mediated chemo‐ and regio‐selective functionalization of allenic C(sp2)−H bond via direct HAA from C(sp2)−H ...bond of allene remains an unsolved challenge in synthetic chemistry. This is primarily due to inherent challenges with addition of radical intermediates to allenes, regioselectivity of HAA process, instability of allenyl radical toward propargyl radical et al. Herein, we report a copper catalyzed allenic C(sp2)−H cyanation of an array of tri‐ and di‐substituted allenes with exceptional site‐selectivity, while mono‐substituted allene was successfully cyanated, albeit with a low yield. In the developed strategy, steric N‐fluoro‐N‐alkylsulfonamide, serving as precursor of hydrogen atom or, plays a crucial role in achieving the desired regioselectivity and avoiding addition of N‐centered radical to allene.
While hydrogen atom ion (HAA) from C(sp3)−H bond has been well explored, radical‐mediated chemo‐ and regioselective allenic C(sp2)−H bond functionalization via direct HAA from the allene represents an inherent challenge and remains an unsolved problem. Herein, we report a copper catalyzed allenic C(sp2)−H cyanation of several tri‐, di‐ and mono‐substituted allenes with exceptional site‐selectivity.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SBCE, SBMB, UL, UM, UPUK
We describe the application of S−H bond insertion reactions of aryl diazoacetates with cysteine residues that enabled metal‐free, S−H functionalization under visible‐light conditions. Moreover, this ...process could be intensified by a continuous‐flow photomicroreactor on the acceleration of the reaction (6.5 min residence time). The batch and flow protocols described were applied to obtain a wide range of functionalized cysteine derivatives and cysteine‐containing dipeptides, thus providing a straightforward and general platform for their functionalizations in mild conditions.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SBCE, SBMB, UL, UM, UPUK
A new cascade three-component halosulfonylation of 1,7-enynes for efficient synthesis of densely functionalized 3,4-dihydroquinolin-2(1H)-ones has been established from readily accessible ...arylsulfonyl hydrazides and NIS (or NBS). The reaction pathway involves in situ-generated sulfonyl radical-triggered α,β-conjugated addition/6-exo-dig cyclization/radical coupling sequence, resulting in continuous multiple bond-forming events including C-S, C-C and C-I (or C-Br) bonds to rapidly build up molecular complexity.
An efficient photoredox‐catalyzed halo‐trifluoromethylation reaction of 1,7‐enynes has been developed under mild conditions. This photocatalytic protocol provides an efficient and functional strategy ...leading to CF3− and halogen‐containing 3,4‐dihydroquinolin‐2(1H)‐ones from a wide range of 1,7‐enynes through two different radical pathways. The reaction mechanism was proposed based on the control experiments.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SBCE, SBMB, UL, UM, UPUK
Considering their unique roles in organic synthesis, and pharmaceutical and agrochemical applications, the development of fluoroalkylation, cyclization, and indole oxidative cleavage are important ...topics. Herein, an unprecedented electrochemical tri‐ and difluoromethylation/cyclization/indole oxidative cleavage process occurring in an undivided cell is presented. The protocol employs a readily prepared Langlois reagent as the fluoroalkyl source, affording a series of tri‐ or difluoromethylated 2‐(2‐acetylphenyl)isoquinoline‐1,3‐diones in good yields with excellent stereoselectivity. It is worth noting that this new methodology merges the fluoroalkylation/cyclization of N‐substituted acrylamide alkenes with the oxidative cleavage of an indole C(2)=C(3) bond under external oxidant‐free conditions.
Tri‐ and difluoromethylation/cyclization/indole oxidative cleavage: An unprecedented electrochemical tri‐ and difluoromethylation/cyclization/indole oxidative cleavage process has been established in an undivided cell. The protocol employs a readily prepared Langlois reagent as the fluoroalkyl source, affording a series of tri‐ or difluoromethylated 2‐(2‐acetylphenyl)isoquinoline‐1,3‐diones in good yields with excellent stereoselectivity.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SBCE, SBMB, UL, UM, UPUK
Silver-mediated C(sp3)–H functionalization and 6-endo-dig oxo-cyclization of conjugated β-alkynyl ketones have been established under oxidative conditions. The reaction leads to the concise ...formation of a wide range of isochromenes via C(sp3)–H bond-breaking and radical addition steps. Dual and monofunctional isochromene products were selectively controlled by using either electron-rich or electron-deficient radical sources.
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A new one‐pot, two‐step silver‐catalyzed spiroketalization of the in‐situ generated quinone imine ketals (QIKs) with β‐alkynyl ketones has been established, enabling multiple C−O and C−C bond‐forming ...reactions to access densely functionalized spirobenzofuran‐2,1′‐isochromene derivatives with generally good yields. The use of β‐alkynyl ketones bearing alkyl and aryl groups located at the α‐position of the carbonyl group could lead to highly diastereoselective spirochromane‐2,1′‐isochromene derivatives. The reaction features broad substrate scope, mild oxidative catalytic conditions and excellent diastereoselectivity.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SBCE, SBMB, UL, UM, UPUK
A novel three‐component selenosulfonation of 1,7‐enynes with sulfinic acids and diphenyl diselenides for the formation of multifunctional 3,4‐dihydroquinolin‐2(1H)‐ones was developed in batch and ...flow. This room‐temperature protocol provides a highly efficient approach to diverse selenosulfones in moderate to excellent yields and with a broad scope of substrates. It should provide a potential synthesis method for the construction of diverse and meaningful 3,4‐dihydroquinolin‐2(1H)‐ones derivatives in the fields of pharmaceutical and biological chemistry. Additionally, an obvious acceleration (20 h to 43 s) was obtained under micro flow conditions.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SBCE, SBMB, UL, UM, UPUK
A direct electrooxidative sulfonylation/heteroarylation reaction of alkenes with sulfinic acids, which proceeds through distal heteroaryl ipso-migration and C–S and C–C bond formations, is reported. ...This electro-synthetic method offers an efficient and environmentally friendly entry to prepare various sulfonated functionalized heteroarenes under an undivided cell at room temperature, avoiding the use of any metal catalysts, additives, and oxidants. Preliminary mechanistic studies indicated a radical pathway.
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