title: Electrophile-integrating Smiles rearrangement provides previously inaccessible C4'-O-alkyl heptamethine cyanine fluorophores.
abstract: New synthetic methods to rapidly access useful fluorophores are needed to advance modern molecular imaging techniques. A new variant of the classical Smiles rearrangement is reported that enables the efficient synthesis of previously inaccessible C4'-O-alkyl heptamethine cyanines. The key reaction involves N- to O-transposition with selective electrophile incorporation on nitrogen. A representative fluorophore exhibits excellent resistance to thiol nucleophiles, undergoes productive bioconjugation, and can be used in near-IR fluorescence imaging applications.
authors.affiliation: Chemical Biology Laboratory, National Cancer Institute, National Institutes of Health , Frederick, Maryland 21702, United States.
authors.forename: Roger R
authors.initials: RR
authors.lastname: Nani
authors.forename: James B
authors.initials: JB
authors.lastname: Shaum
authors.forename: Alexander P
authors.initials: AP
authors.lastname: Gorka
authors.forename: Martin J
authors.initials: MJ
authors.lastname: Schnermann
mesh_terms: D002232:Carbocyanines / Q000138:chemical synthesis* / Q000737:chemistry*; D005456:Fluorescent Dyes / Q000138:chemical synthesis* / Q000737:chemistry; D007476:Ionophores / Q000737:chemistry; D015394:Molecular Structure; D009584:Nitrogen / Q000737:chemistry; D010100:Oxygen / Q000737:chemistry; D019265:Spectroscopy, Near-Infrared / Q000379:methods
chemical_list: D002232:Carbocyanines; D005456:Fluorescent Dyes; D007476:Ionophores; D009584:Nitrogen; D010100:Oxygen