Preparation of beta- and gamma-lactams via ring closures of unsaturated carbamoyl radicals derived from 1-carbamoyl-1-methylcyclohexa-2,5-dienes

AF Bella, LV Jackson, John Christopher Walton

Research output: Other contribution

41 Citations (Scopus)

Abstract

1-Carbamoyl-1-methylcyclohexa-2,5-dienes produced the corresponding delocalised 1-carbamoyl-1-methylcyclohexa-2,5-dienyl radicals on treatment with radical initiators. At temperatures above ca. 300 K dissociation to produce toluene and aminoacyl (carbamoyl) radicals took place. The alternative dissociation of the 1-carbamoyl-1-methylcyclohexa-2,5-dienyl radicals to release methyl radicals and an aromatic amide did not compete. Aminoacyl radicals with allyl, butenyl or similar side chains underwent cyclisations. Moderate yields of N-benzyl-azetidin-2-ones and N-benzyl-pyrrolidin-2-ones were isolated for a range of substituents. The main by-products were N-benzyl-N-alkenylformamides. Ring closure did not take place to a significant extent for precursors with alk-2-ynyl or 2-cyanoalkyl side chains. An improved yield of 1,3-dibenzylazetidin-2-one was obtained by use of lauroyl peroxide as initiator and by inclusion of methyl thioglycolate as polarity reversal catalyst.

Original languageEnglish
Volume2
DOIs
Publication statusPublished - 7 Feb 2004

Keywords

  • SYSTEMATIC STRUCTURAL MODIFICATIONS
  • POLARITY-REVERSAL CATALYSTS
  • SILYLATED CYCLOHEXADIENES
  • BETA,GAMMA-UNSATURATED KETONES
  • STEREOSELECTIVE SYNTHESIS
  • CYCLIZATION
  • DERIVATIVES
  • CYCLOHEXA-1,4-DIENE-3-CARBOXYLATES
  • 2,5-DIHYDROFURAN-2-CARBOXYLATES
  • PHOTOCHEMISTRY

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