4',5'-Dichloro-2',7'-dimethoxy-5(6)-carboxyfluorescein (JOE): synthesis and spectral properties of oligonucleotide conjugates

  • J Org Chem. 2012 Jan 20;77(2):977-84. doi: 10.1021/jo202229t.
Dmitry A Tsybulsky  1 ,  Maksim V Kvach ,  Irina A Stepanova ,  Vladimir A Korshun ,  Vadim V Shmanai
Affiliations
  • 1. Institute of Physical Organic Chemistry, Surganova 13, 220072 Minsk, Belarus.
PMID: 22148236 DOI: 10.1021/jo202229t
Abstract

A convenient procedure for the preparation of the Fluorescent Dye 4',5'-dichloro-2',7'-dimethoxy-5(6)-carboxyfluorescein (JOE) is reported; the overall yield achieved starting from isovanillin is 10 times higher (40% vs 4%) compared to the known procedure. Isomers (5- and 6-) are easily chromatographically separable as pentafluorophenyl esters of 3',6'-O-bis(cyclohexylcarbonyl) derivatives. Four non-nucleoside JOE phosphoramidites based on 5- and 6-isomers and flexible 6-aminohexanol (AH) or rigid 4-trans-aminocyclohexanol (ACH) linkers have been prepared and used for oligonucleotide labeling. Spectral and photophysical properties of 5'-JOE-modified oligonucleotides have been studied. Fluorescence quantum yield of the dye correlates with the nature of the linker (rigid vs flexible) and with the presence of dG nucleosides in close proximity to a JOE residue.

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