Synthesis of 2-Alkylsulfonyl-imidazoles with Three Diversity Positions from Immobilized α-Acylamino Ketones

ACS Comb Sci. 2018 Aug 13;20(8):467-471. doi: 10.1021/acscombsci.8b00075. Epub 2018 Jul 10.

Abstract

The synthesis of novel imidazole derivatives via immobilized α-acylamino ketones is reported in this article. The key intermediates were prepared from the Wang-piperazine resin-supported Fmoc-amino acids. After their sulfonylation with 4-nitrobenzenesulfonyl chloride (4-Nos-Cl), followed by alkylation with α-bromoketones and cleavage of Nos group, the resulting α-acylamino ketones were reacted with Fmoc-isothiocyanate. The corresponding Fmoc-thioureas were subjected to the Fmoc-cleavage and spontaneous ring-closure to imidazole scaffold. The resulting imidazole-thiones were alkylated with alkyl halides and oxidized using meta-chloroperbenzoic acid ( mCPBA). Trifluoroacetic acid (TFA)-mediated cleavage yielded the corresponding trisubstituted 2-alkylsulfonyl imidazoles in good crude purity and acceptable overall yields. In the case of sulfides, prepared from alkyl bromides, the unexpected products brominated at the C4 position of the imidazole were obtained.

Keywords: amino acid; bromoketone; imidazole; solid-phase synthesis.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Alkylation
  • Amino Acids / chemistry
  • Cyclization
  • Fluorenes / chemistry
  • Halogenation
  • Imidazoles / chemical synthesis*
  • Ketones / chemistry*
  • Molecular Structure
  • Oxidation-Reduction
  • Piperazine / chemistry
  • Solid-Phase Synthesis Techniques
  • Sulfones / chemistry*
  • Thiones / chemistry
  • Thiourea / analogs & derivatives
  • Thiourea / chemistry
  • Trifluoroacetic Acid / chemistry

Substances

  • Amino Acids
  • Fluorenes
  • Imidazoles
  • Ketones
  • N(alpha)-fluorenylmethyloxycarbonylamino acids
  • Sulfones
  • Thiones
  • Piperazine
  • Trifluoroacetic Acid
  • Thiourea