Redox-Neutral Ruthenium(II)-Catalyzed Enol-Directed Arene C–H Alkylation with Maleimides

Abstract

An enol-assisted regioselective arene C–H alkylation with maleimides is developed under redox-neutral ruthenium(II) catalysis, offering a wide variety of valuable 3-aryl succinimides including amino acid embedded frameworks in good to excellent yields. The products were also aromatized to produce synthetically useful resorcinol-based biaryls. Mechanistic studies support an organometallic pathway with a reversible C–H metalation step for this reaction.

Rh(III)‐Catalyzed C−H Activation/O‐Annulation for Construction of Divergent Spirosuccinimide and Maleimide‐Fused Isochromenes

“…Ag 2 CO 3 , and K 2 S 2 O 8 , failed to provide the desired product 3 a (entries 10-12). Moreover, decreasing or increasing the amount of catalyst and additive employed did not improve the yield (entries [13][14][15][16].…”

“…[15] Recently, Baidya et al established a ruthenium-catalyzed arene CÀ H alkylation of 2-aryl cyclic 1,3-dicarbonyls with maleimides (Scheme 1D). [16] Although a few examples of enoldirected TM-catalyzed CÀ H activation processes have been explored for the reaction of 2-aryl 1,3-dicarbonyls with their corresponding coupling partners, [17] there have been no reports on the synthesis of diversely functionalized isochromenes containing biologically interesting spirosuccinimide and maleimide moieties via CÀ H activation/O-annulation protocol.…”

Palladium-Catalyzed [3 + 2] Annulation of ortho-Substituted Iodoarenes with Maleimides via a Consecutive Double Heck-type Strategy

“… − Due to their significant biological properties and pharmaceutical importance, some notable strategies have been established for attaining such heterocyclic frameworks; for instance, transition metal-catalyzed annulations effectively accomplish such heterotricyclic systems. − Despite the aforementioned notable strategies, there is still enough scope to develop efficient synthetic methodologies to accomplish such heterocyclic products. Mainly, maleimide and its derivatives are highly affordable and simple starting materials; therefore, in recent years, chemists have employed maleimides as leading coupling partners under induced catalytic transformations. − Especially, maleimide-based transition metal-catalyzed C–H activations to construct polycyclic molecules have been developed. − On the other hand, Pd-catalyzed activation of aryl halides and their eventual Heck couplings with olefins were found as one of the promising tools for constructing polycyclic molecules, − which can be extended to maleimides to get polycyclic compounds. However, unfortunately, under basic Pd(0) catalysis, maleimides are susceptible to hydrolysis of imide bonds because of the reaction’s basic pH, which drastically limits the use of maleimides from usual olefin coupling partners .…”