Date of Award
Doctor of Philosophy (PhD)
Marisa C. Kozlowski
The efforts described in this dissertation initially focus on the asymmetric synthesis of axially chiral binaphtho-para- and binaphtho-ortho-quinones, followed by an exploration of their utility in natural product synthesis, development of ligands for asymmetric catalysis, and development as potential sensors. Axially chiral binaphtho-para- and in-in-binaphtho-ortho-quinones were synthesized through a concerted route involving the enantioselective coupling of a hindered 8-substituted 2-naphthol, with a diaza-cis-decalin copper catalyst developed previously by the Kozlowski group. The coupling was achieved in 62% yield and 87% ee (a single trituration produced material of >99% ee). Subsequent transformations led to an 8,8'-hydroxylated binaphthol, which was selectively oxidized to a binaphtho-para-quinone using a Co-salen catalyst or transformed to the in-in-binaphtho-ortho-quinone with o-iodoxybenzoic acid (IBX). Similarly, the out-out-binaphtho-ortho-quinone was synthesized from a 6,6'-hydroxylated binaphthol, using IBX.
Binaphtho-para-quinones were used as key intermediates for the synthesis of the bisanthraquinone natural product (S)-bisoranjidiol. (S)-Bisoranjidiol was synthesized from a 6,6'-dibrominated binaphtho-para-quinone and mixed vinyl ketene acetal, through
a regioselective tandem Diels-Alder/aromatization reaction. This transformation was achieved in 80% yield (~95% per transformation). The synthesis of (S)-bisoranjidiol was completed in 4% yield over 12 steps, and >99% ee. In addition, the synthesis of a reported binaphthalene tetraol natural product was achieved through reduction of an out-out-binaphtho-ortho-quinone. This synthesis led to the structural reassignment of the proposed compound to a tetrabrominated diphenyl ether. Condensation of various phenylenediamines with binaphtho-ortho-quinones led to bisbenzo[a]phenazines, which represent BINOL derivatives with electron-withdrawing groups (pyrazine ring). The in-in-bisbenzo[a]phenazines performed better than BINOL, but did not offer improvements over the electron-deficient BINOL based catalysts/ligands reported for those reactions. The bisbenzo[a]phenazines, in particular the tetrachlorinated derivatives, also displayed a series of interesting properties and colorimetric responses to various stimuli (chromism), which may lead to the development of colorimetric sensors. The properties include mechanochromism, thermochromism, solvatochromism, vapochromism, acidochromism, and fluorescence.
Podlesny, Erin, "Chiral Binaphthoquinones: Versatile Precursors for the Synthesis of Natural Products and Ligands for Asymmetric Catalysis" (2013). Publicly Accessible Penn Dissertations. 685.