Cooperative Silver‐ and Base‐Catalyzed Diastereoselective Cycloaddition of Nitrones with Methylene Isocyanides: Access to 2‐Imidazolinones

Abstract

A protocol involving cooperative silver‐ and base‐catalyzed diastereoselective cycloaddition of nitrones with isocyanides is described, providing access to a wide range of 2‐imidazolinone derivatives with various functional groups as single diastereomers. Varying the base and temperature of the reaction allowed selective access to both diastereomers of the product. A plausible reaction mechanism is proposed and supported by DFT calculations.

Silver‐Catalyzed and Silver‐Promoted Reactions of Isocyanides

“…Liu and Wang's group employed Ag 2 CO 3 as the catalyst in the reaction of nitrones 63 with methylene isocyanides 64. [15] A wide range of 2-imidazolinone derivatives with various functional groups as the single diastereomer were synthesized in good to excellent yields. Furthermore, varying the base and temperature of the reaction allowed selective access to both diastereomers 65 and 66 as shown in Scheme 7.…”

Silver‐Catalyzed [3+1+1] Annulation of Nitrones with Isocyanoacetates as an Approach to 1,4,5‐Trisubstituted Imidazoles

“…Recently, we described a cooperative silver‐ and base‐catalyzed diastereoselective [3+3] cycloaddition of diaryl‐substituted nitrones with methylene isocyanides to furnish 4‐aryl‐2‐imidazolinones [14g] . Surprisingly, attempts of expanding this protocol to alkyl‐substituted nitrones such as 1 a resulted in the formation of the polysubstituted imidazole product 3 a in 22 % yield (Table 1, entry 1).…”

Transition Metal and Inner Transition Metal Catalyzed Amide Derivatives Formation through Isocyanide Chemistry

“…In 2020, Kan, Liu, Wang, and coworkers described a diastereoselective version of this reaction. 111 They applied a cooperative catalytic system of base and Ag 2 CO 3 to promote the reaction. The ratio of cis/trans cycloproducts showed a high dependence on the base and temperature.…”