1,3,5-Tri- and 1,3,4,5-tetra-substituted 1,4-diazepin-2-one solid-phase synthesis

J Comb Chem. 2008 Sep-Oct;10(5):691-9. doi: 10.1021/cc8001052. Epub 2008 Aug 8.

Abstract

Solid-phase syntheses of 1,3,5-tri-substituted and 1,3,4,5-tetra-substituted 1,4-diazepin-2-ones 15-18 have been accomplished by employing inexpensive commercially available alpha- and beta-amino acids on Wang resin. Reductive amination of the imine formed by condensation of Wang aldehyde resin respectively with beta-alaninate 2 and beta-homophenylalaninate 3, followed by aminoacylation with a set of alpha-N-Boc amino acids (Phe epsilon-( Z)-Lys, and Leu) gave tertiary amide resins 7 and 8. Exposure of resins 7 and 8 to an excess of vinyl magnesium bromide in the presence of copper cyanide gave the corresponding gamma,delta-unsaturated ketone resins 9 and 10 by way of a cascade addition. Diazepinones were made by Boc deprotection and intramolecular reductive amination. To diversify the heterocycle, N-alkylation was performed using a series of alkyl halides. Alternatively, diazepinones 15e-g were obtained from treatment of methyl beta-alaninate resins 4 and 20 under similar copper-catalyzed cascade conditions to afford the gamma,delta-unsaturated ketone 21, which was acylated using alpha-N-Fmoc-amino acids (Phe, Trp, gamma-(t-Bu)-Glu). Formation of diazepinones 15 followed a similar protocol, after Fmoc removal with piperidine. Cleavage of the heterocycles with TFA/TES 95:5 gave the N1-p-hydroxybenzyl diazepinones 15-18 in overall isolated yields from 6 to 24% after purification in purities ranging from 81 to 100% according to LCMS analysis.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Aldehydes / chemistry
  • Amides / chemistry
  • Amination
  • Amino Acids / chemistry*
  • Aminoacylation
  • Azepines / chemical synthesis*
  • Bromides / chemistry
  • Chromatography, Liquid
  • Copper / chemistry
  • Cyanides / chemistry
  • Imines / chemistry
  • Ketones / chemistry
  • Mass Spectrometry
  • Models, Chemical
  • Resins, Synthetic / chemistry*
  • Vinyl Compounds / chemistry

Substances

  • Aldehydes
  • Amides
  • Amino Acids
  • Azepines
  • Bromides
  • Cyanides
  • Imines
  • Ketones
  • Resins, Synthetic
  • Vinyl Compounds
  • Copper