Indium Tribromide Catalyzed Cross‐Claisen Condensation between Carboxylic Acids and Ketene Silyl Acetals Using Alkoxyhydrosilanes

InBr3 catalyzed tandem construction of C–C, C–O and C–N bonds: a concise, convenient and atom-economical strategy for the synthesis of spiro oxazolidine oxindole derivatives

“…We also ascertained that heating decreases the yield (entry 18). Two control experiments were also performed one without using catalyst (entry 19) and another one without base (entry 20), no yield was observed in either case. Encouraged by the initial success in production of spiro oxazolidine oxindole, we investigated the general scope and versatility of this strategy in the synthesis of substituted spiro oxazolidine oxindole, for which we examined the cyclization of structurally different isatins with arylacetylenes and N-tosyl aldimines containing both electron-donating and electronwithdrawing groups and also heteroaryl group.…”

“…Thus due to highly pronounced pharmacological activities displayed by these structurally diverse spirocyclic oxindole, it has attracted considerable attention from organic chemists, resulting in the development of biologically promising analogues that are often more efficacious than the original natural products 13,14 . Similarly, substituted oxazolidine moieties have been exploited successfully in medicinally valuable compounds such as the anticancer prodrugs doxazolidine, doxoform, and doxazcarbamate 15 and also as chiral auxiliaries for synthesis of many chiral compounds [16][17][18] Figure 1 Natural Products containing spirooxindole skeleton Significant attention has recently been paid to the use of indium salts as green Lewis acid in organic synthesis [19][20][21][22] . In many cases, indium halides have advantages of non-toxicity, stability in air and water and strong tolerance to oxygen-and nitrogen-containing substrates than the conventional lewis acids.…”

Gallium and Indium Compounds in Homogeneous Catalysis

“…74 The reaction proceeds via initial formation of a trimethoxysilyl carboxylate and hydrogen gas. The silyl carboxylate may then be activated by the Lewis acidic In(III) center toward a nucleophilic attack from the ketene silyl acetal to afford the final β-keto ester and trimethylsilyl trimethoxysilyl ether.…”

Chemistry of Fluorinated Carbon Acids: Synthesis, Physicochemical Properties, and Catalysis

“…As an example to illustrate the distinguishing features of 17, we found the unusual olefination reaction of lactones using ketene silyl acetals. 54) In general, the reactions of carboxylic acid derivatives with silicon enolates give the corresponding Claisen condensation product E 55,56) (Chart 32). In similar reactions, silyl acetal D, which is a simple adduct of the silicon enolate to the starting ester, was often isolated.…”