Reaction of α-(N-Carbamoyl)alkylcuprates with Propargyl Substrates:  Synthetic Route to α-Amino Allenes and Δ3-Pyrrolines

Carbamate deprotonation followed by treatment with CuCN·2LiCl affords α-(N-carbamoyl)alkylcuprates which react with propargyl halides, mesylates, tosylates, phosphates, acetates, and epoxides to give α-(N-carbamoyl) allenes via an anti-SN2‘ substitution process. Propargyl halides, sulfonates, and phosphates give good yields of carbamoyl allenes, while the acetates afford low yields. Propargyl substrates undergo regiospecific SN2‘ substitution in the absence of severe steric hindrance. The α-(N-carbamoyl) allenes can be cyclized to 2-oxazolidinones or deprotected to afford the free amines which can be cyclized to Δ3-pyrrolines with either AgNO3 or Ru3(CO)12.