A concise synthesis of the Pennsylvania Green fluorophore and labeling of intracellular targets with O6-benzylguanine derivatives

Org Lett. 2007 Sep 13;9(19):3741-4. doi: 10.1021/ol7015093. Epub 2007 Aug 17.


We report improved syntheses of the Pennsylvania Green and 4-carboxy-Pennsylvania Green fluorophores; the latter compound was prepared from methyl 4-iodo-3-methylbenzoate in a three-pot process (32% overall yield). Chinese hamster ovary cells expressing O6-alkylguanine-DNA alkyltransferase fusion proteins were treated with Pennsylvania Green and Oregon Green linked to O6-benzylguanine (SNAP-Tag substrates). Analysis of living cells by confocal microscopy revealed that Pennsylvania Green derivatives exhibit substantially higher cell permeability than analogous Oregon Green-derived molecular probes.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Alkyl and Aryl Transferases / chemistry
  • Alkyl and Aryl Transferases / metabolism
  • Animals
  • CHO Cells
  • Cricetinae
  • Cricetulus
  • Crystallography, X-Ray
  • Fluorescent Dyes / chemical synthesis*
  • Fluorescent Dyes / chemistry
  • Genes, Reporter / genetics
  • Guanine / analogs & derivatives*
  • Guanine / chemistry
  • Humans
  • Models, Molecular
  • Molecular Probes / chemistry
  • Molecular Structure


  • Fluorescent Dyes
  • Molecular Probes
  • O(6)-benzylguanine
  • Guanine
  • Alkyl and Aryl Transferases
  • DNA alkyltransferase