Diversification of Nucleophile-Intercepted Beckmann Fragmentation Products and Related Density Functional Theory Studies

Synthesis of Functionalized Hexahydrocarbazoles by Beckmann Elimination and Nucleophile-Intercepted Beckmann Fragmentation

The Beckmann elimination and nucleophile-intercepted Beckmann fragmentation (NuBFr) of oximes starting from regioisomeric indolinyl bicyclic ketones lead to products that are subjected to further synthetic manipulations and ultimately result in the stereospecific formation of densely functionalized hexahydrocarbazoles. The Pd-catalyzed Suzuki-Miyaura cross-coupling reaction of a key alkenyl bromide intermediate with various boronic acids gives arylated products.

Synthesis of 2-(Cyanomethyl)benzoic Esters via Carbon-Carbon Bond Cleavage of Indanones

A novel synthesis of 2-(cyanomethyl)benzoic esters from indanone derivatives has been established. This reaction proceeds via a deprotonation of alcohols with a chemical base, followed by a nucleophilic addition to indanones and Beckmann fragmentation. In addition, this reaction could also work under electrochemical conditions, and no external chemical bases were needed. This mild method offers a novel strategy for the late-stage functionalization of various natural alcohols.

Synthesis of Carbamoyl Fluorides via a Selective Fluorinative Beckmann Fragmentation

A fluorinative Beckmann fragmentation of α-oximinoamides was devised to provide synthetically useful carbamoyl fluorides. High selectivity for fragmentation over a potentially competing Beckmann rearrangement was observed. This protocol has a distinct mechanism and thus a different substrate scope compared with other synthetic methods. α-Oximinoamides derived from the readily available secondary amines, lactams, or isatins were converted into structurally diverse carbamoyl fluorides.