TiO₂ Photocatalyzed Oxidative Coupling of Phenols and Related Compounds Jingze Wu

Format:

Book

Thesis/Dissertation

Author/Creator:

Wu, Jingze, author.

Contributor:

University of Pennsylvania. Chemistry., degree granting institution.

Language:

English

Subjects (All):

0485.

0486.

0490.

Local Subjects:

0485.

0486.

0490.

Physical Description:

1 electronic resource (519 pages)

Contained In:

Dissertations Abstracts International 87-07B

Place of Publication:

Ann Arbor : ProQuest Dissertations and Theses, 2025

Language Note:

English

Summary:

Phenols and their derivatives serve as fundamental building blocks for numerous classes of complex molecules that play essential roles in biological systems. Nature has evolved selective oxidative coupling strategies for phenolic substrates, and chemists have long sought to replicate these transformations. However, oxidative phenol coupling requires substrates with accessible redox potentials, and as a result, nearly all reported catalytic methods are limited to electron-rich phenols. The absence of electron-deficient phenolic motifs in many natural products underscores the difficulty, even for enzymatic systems, of engaging more challenging substrates. Moreover, phenol overoxidation has long impeded the development of general catalytic oxidative coupling methods. These persistent limitations have significantly restricted progress in the field and hindered the emergence of more efficient and broadly applicable approaches. Titanium dioxide (TiO₂), photocatalytic activity of which was first recognized in the 1980s, has seen widespread industrial use in pollutant degradation. However, its role in organic photocatalysis has been limited by its wide band gap and the requirement for UV light activation. In this thesis, I present a novel approach to phenol oxidative coupling that employs TiO₂ as a photocatalyst under blue light irradiation. Central to this advancement is ligand-to-metal charge transfer (LMCT) mechanism, in which phenols interact with the TiO₂ surface to form visible-light-absorbing complexes, enabling oxidative coupling of substrates with diverse electronic profiles. Furthermore, by leveraging in-situ boron-biphenol complexation, the resulting biphenols can be selectively sequestered from the reaction environment, allowing for controlled and selective oxidation of phenol monomers. This work establishes the first general photocatalytic method for the oxidative coupling of both electron-deficient and monosubstituted phenols. By overcoming a long-standing challenge in oxidative phenol coupling, this study broadens the scope of catalytic oxidative transformations and paves the way for new applications in pharmaceutical synthesis and materials science. Beyond biphenols, this strategy also enables efficient access to complex natural product motifs. In particular, the dihydrobenzofuran core of α-O-β-5 neolignans, common in bioactive natural products, can be constructed through visible-light-driven β-5' coupling of alkenyl phenols and phenols on the TiO₂ surface. The method proceeds under mild, sustainable conditions, using a recyclable photocatalyst and air as the sole oxidant, delivering dihydrobenzofurans with high chemo- and regioselectivity

Notes:

Advisors: Kozlowski, Marisa C.; Zahrt, Andrew Committee members: McCallum, Monica; Huryn, Donna

Source: Dissertations Abstracts International, Volume: 87-07, Section: B.

Ph.D. University of Pennsylvania 2025

Vendor supplied data

Local Notes:

School code: 0175

ISBN:

9798276005607

Access Restriction:

Restricted for use by site license