Decarboxylative Halogenation of Heterocycles Enabled by Vanadium Haloperoxidases

Description

Despite comprising a variety of bioactive compounds that can be utilized as effective synthetic precursors, the construction of halogenated arenes often relies on hazardous reagents and conditions that pose regioselectivity issues in complex systems. Halodecarboxylation using vanadium-dependent haloperoxidases (VHPOs) has

Despite comprising a variety of bioactive compounds that can be utilized as effective synthetic precursors, the construction of halogenated arenes often relies on hazardous reagents and conditions that pose regioselectivity issues in complex systems. Halodecarboxylation using vanadium-dependent haloperoxidases (VHPOs) has emerged as a sustainable alternative for the synthesis of halogenated arenes. In the Biegasiewicz group, we recently discovered that VHPOs can furnish 3-bromooxindoles from 3-carboxyindoles through a decarboxylation event, followed by oxidation. While this tandem process was exciting, the intermediates of this process, 3- bromoindoles are independently valuable reagents, which necessitated further investigation. Herein we examine the biocatalytic access to bromoindoles for which we addressed the major challenge of undesired oxidation event. The first preventative approach acylated the indole nitrogen, resulting in 1-acetylindole-3-CO2H. This could then be subjected to optimized enzymatic bromination conditions to produce 1-acetyl-3-bromoindole in 98% yield with CiVCPO. The second preventative approach was to modify the reaction conditions, furnishing 1-methyl-3-bromoindole in 73% yield from 1-methylindole-3- CO2H with AmVBPO.

Date Created
2023-05
Agent

Biocatalytic Halocyclization of Amides Enables By Vanadium Haloperoxidases

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Description
Marine algae are a rich source of bioactive halogenated natural products. Thepresence of these marine natural products has largely been attributed to their biosynthesis by organisms in these environments through a variety of different halogenation mechanisms. One of the key contributors in

Marine algae are a rich source of bioactive halogenated natural products. Thepresence of these marine natural products has largely been attributed to their biosynthesis by organisms in these environments through a variety of different halogenation mechanisms. One of the key contributors in these halogenation processes are from the vanadium haloperoxidases (VHPOs) class of enzymes. VHPOs perform an electrophilic halogenation through the oxidation of halide ions with hydrogen peroxide as the terminal oxidant. This technique produces an electrophilic halide equivalent that can directly halogenate organic substrates. Despite the numerous known reaction capabilities of this enzyme class, their construction of intramolecular ring formation between a carbon and nitrogen atom has remained unreported. Herein, this study presents a development of a ‘new to nature’ chemical reaction for lactam synthesis. In pursuit of this type of reaction, it was discovered that wild type VHPOs (e.g., Curvularia inaequalis, Corallina officinalis, Corallina pilulifera, Acaryochloria marina) produce halogenated iminolactone compounds from acyclic amides in excellent yields and selectivity greater than 99 percent yield. The extension to chlorocyclizations will also be discussed.
Date Created
2022
Agent

Mechanisms of Photodegradation of Fe Catalysts and Small Organic Molecules

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Description

This thesis is about how Fe catalysts can be degraded using photocatalysis and how Fe catalysts can degrade small molecules in conjunction with light. The goal of this paper is to look further into more sustainable methods of organic chemistry.

This thesis is about how Fe catalysts can be degraded using photocatalysis and how Fe catalysts can degrade small molecules in conjunction with light. The goal of this paper is to look further into more sustainable methods of organic chemistry. Many current organic chemistry practices involve the use of precious metals. Iron is a more sustainable catalyst because it is abundant and inexpensive which is important for preserving the earth and making the organic chemistry more accessible. Along the same lines, light is a renewable energy source and has demonstrated its ability to aid in reactions. Overall, the goal of this paper is to explore the more sustainable alternatives to harsh and toxic organic chemistry practices through the use of Iron and light.

Date Created
2022-05
Agent

Development of a Terpene Cyclase Using Oxyanion Hole Biocatalysis

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Description

Terpene cyclizations are one of the most complex reactions that occur in nature. Scientists have found that replicating this reaction in a lab setting has proved to be immensely challenging as result of the numerous intermediates that must be controlled

Terpene cyclizations are one of the most complex reactions that occur in nature. Scientists have found that replicating this reaction in a lab setting has proved to be immensely challenging as result of the numerous intermediates that must be controlled through the cyclization process in the absence of an enzyme. This study uses commercially available lipases to conduct reactions with geraniol-derived starting materials to identify conditions for performing a terpene cyclization effectively and efficiently. Through hypothesized screening of enzymes and reaction conditions, we have identified a protocol for the successful cyclization of limonene and other geranyl-derived products.

Date Created
2021-05
Agent