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Towards Synthesis of an Analogue to Betanin: The Synthesis of Tert-butyl-4-methylene-3,4- dihydropyridine-1(2H)-carboxylate and the Extension of the Electrophilic π Highway

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Title: Towards Synthesis of an Analogue to Betanin: The Synthesis of Tert-butyl-4-methylene-3,4- dihydropyridine-1(2H)-carboxylate and the Extension of the Electrophilic π Highway
Author: Joe, Candice L.
Advisor: Newirth, Terry
Department: Haverford College. Department of Chemistry
Type: Thesis (B.S.)
Issue Date: 2008
Abstract: Betanin is the naturally occurring glycoside which gives beets their characteristic red color. Also used as a natural food dye, betanin has been tested for sensitivity to pH, heat, oxygen and light. Despite its structurally conjugated electrophilic system which acts as a highway to connect the nitrogen atom of a piperidine lower ring with the iminium ion of the indolelike upper ring, its sensitivity to nucleophiles has yet to be explored (Figure 1b). Our previous research has shown that cysteine does affect the chromophore of crude beet extract. The primary focus of this research is to develop a multi-step synthesis of an analogue to betanin in order to study its reactivity with thiols, a functional group common in many foods. The two major challenges have been to create the exo and internal double bonds of the lower ring. We are exploring both Wittig and metathesis routes for the exo double bond. This study focuses on the synthesis of the 6-7- unsaturated ketone 11, which can then be used to make the exo-double bond via a Wittig reaction. Experiments conducted thus far have been successful in the synthesis of tert-butyl-4-methylene-3,4- dihydropyridine-1(2H)-carboxylate (12), which is a precursor to a “stripped down” betalamic acid analogue. The electrophilic electron highway can be further extended by olefin metathesis. This route could provide a shorter synthetic scheme and a simpler model for our reactivity studies.
Subject: Ketones -- Synthesis
Subject: Betanin -- Synthesis
Subject: Wittig reaction
Terms of Use: http://creativecommons.org/licenses/by-nc/3.0/us/
Permanent URL: http://hdl.handle.net/10066/9302

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Citation

Joe, Candice L.. "Towards Synthesis of an Analogue to Betanin: The Synthesis of Tert-butyl-4-methylene-3,4- dihydropyridine-1(2H)-carboxylate and the Extension of the Electrophilic π Highway". 2008. Available electronically from http://hdl.handle.net/10066/9302.

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http://creativecommons.org/licenses/by-nc/3.0/us/ Except where otherwise noted, this item's license is described as http://creativecommons.org/licenses/by-nc/3.0/us/

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