This Review summarizes the development of catalytic asymmetric dearomatization (CADA) reactions. The CADA reactions discussed herein include oxidative dearomatization reactions, dearomatization by Diels-Alder and related reactions, the alkylative dearomatization of electron-rich arenes, transition-metal-catalyzed dearomatization reactions, cascade sequences involving asymmetric dearomatization as the key step, and nucleophilic dearomatization reactions of pyridinium derivatives. Asymmetric dearomatization reactions with chiral auxiliaries and catalytic asymmetric reactions of dearomatized substrates are also briefly introduced. This Review intends to provide a concept for catalytic asymmetric dearomatization.
[Structure: see text] A new method for direct phosphonation of thiazoles, furans, and pyrroles is introduced. Reactions of the heteroaryl compounds with dimethyl or diethyl phosphites and Mn(OAc)(3).2H2O under mild conditions give phosphonated products in high yield and good regioselectivity.
A one‐pot methodology to synthesize metastable bicyclic 2,5‐dihydrooxepines from cyclic 1,3‐diketones and 1,4‐dibromo‐2‐butenes through the retro‐Claisen rearrangement of syn‐2‐vinylcyclopropyl diketone intermediates is reported. DFT calculations were performed to understand the reaction selectivity and mechanisms towards [1,3]‐ or [3,3]‐sigmatropic rearrangements, highlighting the crucial influence of the temperature. The reaction was successfully applied to a short protecting group‐free total synthesis of radulanin A, a natural 2,5‐dihydrobenzoxepine. Moreover, the strong herbicidal potential of this natural product is demonstrated for the first time.
An efficient protocol for the synthesis of indenones has been developed via the annulation of benzoic esters and internal alkynes by exploiting the cobalt catalyst.
The N-S bond-based internal oxidant offers a distinct approach for the synthesis of highly functionalized pyridines. A novel Rh(III)-catalyzed one-pot process undergoes an efficient C-C/C-N bond formation along with desulfonylation under very mild conditions. The method is quite simple, general, and efficient.
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