The ability to track cations in living cells using fluorescent sensors is important for scientists to understand the cellular mechanisms of those ions. The ability to track lithium ion is of specific interest as it would assist researchers in understanding the role lithium salts play in treating bipolar disorder. A coumarin-based molecule was substituted, using a methylene bridge, with a 1-aza-9-crown ether at the 3-position for this purpose. Following published procedures, 8-hydroxyjulolidine-9-carboxaldehyde and diethylmalonate were reacted to form the coumarin ring system by a Knoevenagel condensation. The resulting ester was hydrolyzed from the 3-position by strong acid and replaced with an aldehyde via a Vilsmeier-Haack reaction. The final three steps of the six-step synthetic pathway to yield the target molecule were adapted from the literature. These included a reductive amination with benzylamine followed by deprotection through catalytic hydrogenation to yield a primary amine. Subsequent reaction with 1,2-bis(2-iodoethyoxy)ethane generates the 1-aza-9-crown-3 ring to complete the synthesis. The final product will be titrated with biologically relevant cations to determine binding constants.

Synthesis of a 1-aza-9-crown-3-substituted coumarin for fluorescence living cell sensing of metal ions

251st National Meeting (2016)

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