Synthesis of the Angiotensin Converting Enzyme Inhibitor (−)-A58365A via an Cycloaddition Reaction

[formula: see text] The angiotensin converting enzyme inhibitor (-)-A58365A (1) was synthesized by a process based on the [3 + 2]-cycloaddition reaction of a phenylsulfonyl-substituted isomünchnone intermediate. The starting material for this process was prepared from L-pyroglutamic acid and involved using a diazo-phenylsulfonyl-substituted pyrrolidine imide. Treatment of the diazoimide with Rh2(OAc)4 in the presence of methyl vinyl ketone afforded a 3-hydroxy-2-pyridone derivative which was subsequently converted to the ACE inhibitor in six additional steps.