Copper‐Catalyzed Aerobic Oxidative Cleavage of Unstrained Carbon‐Carbon Bonds of 1,1‐Disubstituted Alkenes with Sulfonyl Hydrazides

Abstract

Carbon-carbon cleavage | Alkoxy radical | Copper-catalyzed | 1,1-Disubstituted alkenes | Sulfonyl hydrazides Alkoxy radical-mediated carbon-carbon bond cleavages have emerged as a powerful strategy to complement traditional ionic-type transformations. However, carbon-carbon cleavage reaction triggered by alkoxy radical intermediate derived from the combination of alkyl radical and dioxygen, is scarce and underdeveloped. Herein, we report alkoxy radical, which was generated from alkyl radical and dioxygen, mediated selective cleavage of unstrained carbon-carbon bond for the oxysulfonylation of 1,1-disubstituted alkenes, providing facile access to a variety of valuable β-keto sulfones. Mechanistic experiments indicated alkoxy radical intermediate that underwent subsequent regioselective β-scission might be involved in the reaction and preliminary computational studies were conducted to provide a detailed explanation on the regioselectivity of the CC bond cleavage. Notably, the strategy was successfully applied for constructing uneasily obtained architecturally intriguing molecules.

Metal‐Free Photocatalytic [4+2] Annulation of Acrylamides with 2‐Benzyl‐2‐bromocarbonyls to Assemble Tetralin‐1‐carboxamides

“…Now, we envisioned whether the linear starting material 2‐benzyl‐2‐bromocarbonyls could be used as C4‐synthons and react with the other linear starting material acrylamides (radical acceptors) to undergo a cascade C(sp 3 )−Br/C(sp 2 )−H bond functionalization, double C−C bond formation, and aromatization sequence, thus providing access to highly valuable tetralin‐1‐carboxamide architectures. As a part of our ongoing research toward the radical‐induced construction of heteroatom‐containing compounds, [ 15‐16 ] we herein report an example of visible‐light‐induced [4+2] annulation of acrylamides with 2‐benzyl‐2‐bromocarbonyls, providing a mild, metal‐free, and additive‐free approach for the construction of diverse functionalized tetralin‐1‐carboxamides (Scheme 1C). Interestingly, the conversion of the resulting tetralin‐1‐carboxamides into novel bridged polycyclic imides with excellent cis ‐diastereoselectivities via the LiCl‐mediated mono‐decarboxylative cyclization was also described.…”

Nickel-Catalyzed Suzuki–Miyaura Coupling in Water for the Synthesis of 2-Aryl Allyl Phosphonates and Sulfones

“…The straightforward method for the preparation of 2-aryl allyl sulfones involves the oxidation of allylic sulfides 13 and the reaction of α-bromomethylstyrenes with arylsulfinates. 14 Sulfonyl radical generated from sulfinic acids, 15 sulfonyl hydrazides catalyzed by Cu under an O 2 atmosphere, 16 FeCl 3 , 17 or tetrabutylammonium iodide (TBAI), 18 and sodium arylsulfinates catalyzed by I 2 19 in the presence of stoichiometric amounts of peroxide have been effectively developed. p -Toluenesulfonylmethyl isocyanide (TosMIC) has been used as a sulfonylating agent in the presence of catalytic amounts of I 2 , 20 Cu, 21 or Co(salen) 2 22 for the formation of 2-aryl allyl sulfones.…”

Additive-free aerobic oxidative difunctionalization of alkenes with P4S10 and alcohols to access β-hydroxy phosphorodithioates

“…In continuation of our research toward the construction of phosphorus- and sulfur-containing compounds, 14,15 herein, we wish to report a facile and efficient protocol for the synthesis of a series of β-hydroxy phosphorodithioates through additive-free aerobic oxidative difunctionalization of alkenes with P 4 S 10 and alcohols under mild conditions (Scheme 1e). Interestingly, when 2-vinylpyridine and α,β-unsaturated carbonyl compounds were used as substrates, the hydrophosphorodithiolation products could be selectively obtained in good yields.…”