Improved synthesis of DCDHF fluorophores with maleimide functional groups

A group of dicyanodihydrofuran (DCDHF) fluorophores with maleimide functionality has been synthesized. One of the methods used is an aromatic nucleophilic substitution reaction. Another generally useful method is combination of the Mitsunobu reaction of the DCDHF-OH with protected maleimide with a subsequent retro Diels–Alder reaction. A group of dicyanodihydrofuran (DCDHF) fluorophores with thiol-reactive maleimide functionality has been synthesized. One of the methods involves aromatic nucleophilic substitution reaction between an arylfluoride containing DCDHF and an amine containing protected maleimide. An alternative and generally useful method involves combination of the Mitsunobu reaction of a DCDHF-OH with a furan or 2-methylfuran protected maleimide and then subsequent retro Diels–Alder reaction.