Silver catalyzed intramolecular cyclization for synthesis of 3-alkylideneoxindoles via C–H functionalization

Abstract

A novel protocol for the preparation of various 3-alkylideneoxindoles via a silver-catalyzed aromatic C-H functionalization has been developed. The process is simple, environmentally conscious, and avoids the use of abundant bases, oxidants, or other additives.

Aqueous Copper Nitrate Catalyzed Synthesis of 3‐Alkylideneoxindoles from α‐Diazo‐β‐ketoanilides

“…Little difference was observed in the yields for those substrates with electron‐withdrawing or electron‐donating substituents. This phenomenon is consistent with previous reports 9c,9d . N ‐Naphthyl‐α‐diazo‐β‐ketoanilide 4i gave the desired product 5i in good yield (73 %).…”

“…Considering the reaction mechanism, in the AgOTf‐catalyzed system, it was presumed that the free carbene‐generated carbocation underwent an intramolecular aromatic electrophilic addition as a key step 9c. Later, Li and Gao further proposed that the addition was a Ag‐carbene addition process on the basis of their computational results 18.…”

“…Method (v) is thus the most competitive because of its broad substrate scope, its use of a simple catalyst, and the green nature of the process (no toxic byproducts released and only nitrogen produced). Several groups have reported modifications of Method (v) by using different catalysts and solvents, including Rh 2 (OAc) 4 /CH 2 Cl 2 (benzene),9a,9b AgOTf/1,4‐dioxane,9c and [Ru( p ‐cymene)Cl 2 ] 2 /toluene 9d. However, all of these groups used volatile and toxic organic solvents (CH 2 Cl 2 , benzene, and 1,4‐dioxane).…”

Patterns of folliculogenesis in ducks following the administration of a gonadotropin-releasing hormone 1 (GnRH) analogue

“…Therefore, the increase in CL number is likely responsible for the increased progesterone concentrations in the GnRH group. Also, studies on sheep [33] (McNatty and Land, 1979), mouse [11], humans [32], porcine [63], chicken and domestic hen [52] and turkey [46] suggest that low concentration of prolactin is required for synthesis of progesterone, since high concentration of prolactin decreases progesterone levels by stimulating hydroxysteroid dehydrogenase enzyme, which brings about the catabolism of progesterone [52,64]. Similar observation in birds is not clear but prolactin inhibits granulose cell progesterone at high doses [56] but not at lower, physiological doses [17].…”

Au‐ and Pt‐Catalyzed CH Activation/Functionalizations for the Synthesis of Heterocycles

“…The reaction proceeds efficiently with extremely good substrate scope and significant opportunities for structural diversification. This method provides a diazo compound-free access to this type of products [29].…”