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.
