Converting Cycloalkanones into N‐Heterocycles: Formal Synthesis of (‐)‐Gephyrotoxin 287C.

Key step in the synthesis of Kishi′s intermediate (VIII) on the way to the natural alkaloid gephyrotoxin 287C (IX) is the combination of Beckmann ring expansion and photochemical ring contraction to convert cyclopentanone (I) into pyrrolidine (VI) stereospecifically.