A new synthetic method for allene-1,3-dicarboxylates using DMC and a novel tandem cyclization to a pyrrolizidine alkaloid skeleton

Abstract A new one-step synthesis of allene-1,3-dicarboxylates from acetone-1,3-dicarboxylates in high yields was developed by the use of DMC as a dehydrating reagent. This process opened a new expeditious route to a 1-azabicyclo[3.3.0]octane skeleton of pyrrolizidine alkaloids from dimethyl acetone-1,3-dicarboxylate and bis(2-chloroethyl)amine via a Michael addition and a novel tandem cyclization.