Double decarboxylative route to 3-substituted pyrrolidines: Reaction of monoalkyl malonates and related carboxylic acids with sarcosine and formaldehyde

Three-component reactions of monoalkyl malonates, cyanoacetic acids or 2-ketocarboxylic acids, N-methylglycine, and formaldehyde were developed to rapidly access 3-substituted pyrrolidines in 17–97% yield. These reactions represent a double decarboxylative domino-sequence promoted by pyrrolidine and involve N-methylazomethine ylide as the reactive intermediate.