Palladium‐Catalyzed Dehydrogenation/Oxidative Cross‐Coupling Sequence of β‐Heteroatom‐Substituted Ketones

Abstract

Concise and selective: the title one-pot sequence allows formation of the enone functionality and subsequent cross-coupling. The process provides access to highly functionalized cyclic enolones and enaminones from readily accessible β-heteroatom-substituted cyclic ketones.

Palladium-Catalyzed Aerobic Dehydrogenation of Cyclic Hydrocarbons for the Synthesis of Substituted Aromatics and Other Unsaturated Products

“…19 On the other hand, the practicality of the methods, especially for large scale applications, would benefit from lower catalyst loading. Additional synthetic opportunities have been realized through the use of Pd-catalyzed α,β-dehydrogenations of carbonyl compounds in tandem reactions, representative examples of which include dehydrogenation/Heck-type reactions of acyclic aldehydes and ketones 25 , chromanones, 26 and cyclic carbonyl compounds. 27 …”

Ruthenium‐Catalyzed, Keto‐Directed, Site‐Selective C–H Activation of Diverse Chromanones with Alkenes

“…In fact, through this method one can think of further functionalization at the C3 position at a later stage. We envisioned that the alkenylated chromanones may have a wide variety of applications in medicinal chemistry, pharmaceuticals, and natural products chemistry , . Given that chromanone motifs are known to have a wide range of biological activities, we decided to demonstrate a simple and convenient method for keto‐directed ortho ‐olefination through C–H activation by using chromanone derivatives.…”

Recent Developments in Transition Metal‐Catalyzed Cross‐Dehydrogenative Coupling Reactions of Ethers and Thioethers

“…Copper is the transition metal most used for dehydrogenative coupling involving ethers. Soon after the first example was reported by Li and co‐workers in 2006, other substrates were combined with ethers using copper‐catalyzed CDC strategies: ketones coupled using Cu(OTf) 2 /InCl 3 ‐ N ‐hydroxyphthalimide (NHPI)/air and using CuBr 2 ‐TBHP‐AcOH‐pyrrolidine (TBHP =t BuOOH, i. e. tert ‐butyl hydroperoxide), 4‐chromanones, alkynes, methoxy arenes, cinnamic acids via copper‐catalyzed decarboxylative alkenylation, thiazoles and benzothiazoles, and nucleobases (purines and pyrimidines) . Recent developments are highlighted below and divided according to the type of orbitals involved, i. e. sp 3 ‐sp 3 , sp 3 –sp 2 and sp 3 –sp coupling.…”