A Rh(III)-catalyzed annulation between salicylaldehydes and diazo compounds with controllable chemoselectivity is described. AgNTf favored benzofurans via a tandem C-H activation/decarbonylation/annulation process, while AcOH led to chromones through a C-H activation/annulation pathway. The reaction exhibited good functional group tolerance and scalability. Moreover, only a single regioisomer of benzofuran was obtained due to the in situ decarbonylation orientation effect.
The Bu4NI-catalyzed reaction of ketones with benzylic alcohols was achieved, leading to alfa-acyloxycarbonyl compounds in moderate to good yields. This metal-free procedure featured the employment of facilely and commercially available starting materials and TBHP as a clean oxidant with high atom economy.
An FeCl2-promoted carbomethylation of arylacrylamides by di-tert-butyl peroxide (DTBP) is achieved, leading to 3-ethyl-3-substituted indolin-2-one in high yield. The reaction tolerates a series of functional groups, such as cyano, nitro, ethyloxy carbonyl, bromo, chloro, and trifluoromethyl groups. The radical methylation and arylation of the alkenyl group are involved in this reaction.
A tert-butyl peroxybenzoate (TBPB)-promoted direct α-methylation of 1,3-dicarbonyl compounds has been developed, providing α-methyl derivatives in moderate to good yields. In this procedure, TBPB plays a dual role, serving as both the methyl source and radical initiator. This work represents a key complement to the traditional α-methylation of 1,3-dicarbonyl compounds using methyl iodide.
A novel strategy for intercepting the σ-alkylpalladium species generated via a Heck reaction, enabling a palladium-catalyzed cyclization of o-ethynylanilines, has been described. This direct and operationally simple protocol provided a fundamental platform to synthesize bisindoles with high efficiency, involving one C-N bond and two C-C bond formations.
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