Lewis acid-catalyzed one-pot sequential reaction for the synthesis of α-halogenated β-keto esters

Catalytic Nazarov Cyclization: The State of the Art

“…A diamine monotriflate (39) has been shown to catalyze the asymmetric aza-Nazarov reaction of azirines (33), with kinetic resolution of the unreacted material (Scheme 10). [74] The 4p electron conrotation of the azirine in the iminium form (34) generates a cation that is trapped by water.…”

“…Aza-Nazarov reaction of azirines(33). Syntheses of strigolactone analogues containing indoles (28).Scheme 10.…”

Gold‐Catalyzed Cycloisomerization–Halogenation Sequence of 1,3‐Enyne Esters with NXS: Efficient Synthesis of 5‐Bromo/Iodo Cyclopentenones

“…α‐Halo carbonyl compounds such as α‐Brominated and α‐iodinated ketones are not only the core structure moieties existing in biologically natural products and pharmaceuticals, but also serve as the versatile synthetic precursors for the preparation of a wide variety of highly complex molecules, Thus, the development of efficient protocols for the regioselective synthesis of this privileged scaffolds has received increasing attention and numerous methods have been established . By far the most prevalent and straightforward strategies for preparing α‐Bromo and α‐iodo ketones are rely on the halogenation of ketones with molecular bromine or N‐bromosuccinimide (NBS)/N‐iodosuccinimide (NIS) in the presence of Lewis or protic acids.…”

“…Apart from these methods, a variety of synthetic strategies from different class of feedstocks have been realized, including transition‐metals or acid catalyzed hydration of haloalkynes, oxidation of vinyl halides or olefins, direct conversion of alcohols, dearomative halogenation of phenols, and other processes . While remarkable progress has been achieved, current reported methods were still limited to acyclic α‐bromo/iodo ketones, and the synthesis of cyclic enones with a X (Br, I)‐containing all‐substituted stereocenter from readily available acyclic precursors are particularly scarce …”

A Recyclable Fluorous Hydrazine‐1,2Bis(Carbothioate) Organocatalyst for the Synthesis of ꞵ‐Chloroethers with N‐Chlorosuccinimide

“…Many wonderful works were reported and some of them were of great importance. In this paper, we tried to apply the concept of organocatalysis [1][2][3][4][5][6][7][8][9][10][11][12]. Also, inspired by the fluorous-tagging idea, we prepared recyclable organocatalysts fluorous hydrazine-1,2-bis(carbothioate) 1 and hydrazine-1,2-dicarboxylate 2 (Scheme 1) and then applied them to the synthesis of β-chloroethers under mild reaction conditions [7][8][9].…”