Synthesis of cyclopentane annulated δ‐lactams via diazomethane‐mediated CC bond cleavage of α‐keto N,O‐hemiaminals

Diazomethane‐mediated C‐C bond cleavage of α‐keto N,O‐hemiaminals was investigated for the first time. Diazomethane as a reagent result C‐C bond cleavage of norbornyl α‐keto N,O‐hemiaminals, Grob‐like fragmentation, lead to the formation of cyclopentane annulated δ‐lactams in excellent yields. We have synthesized the precursor norbornyl α‐keto N,O‐hemiaminal by the nucleophilic displacement of halogen of norbornyl α‐diketone with the various amines. Herein, first diazomethane‐mediated C‐C bond cleavage of α‐keto N,O‐hemiaminal is reported. The Grob‐like fragmentation, diazomethane as a reagent, of α‐keto N,O‐hemiaminal yielded cyclopentane annulated δ‐lactam in excellent yields, and various α‐keto N,O‐hemiaminals were synthesized from Diels‐Alder adducts via α‐diketones.