Browsing by Author "Wang, Haopei"

Now showing 1 - 3 of 3
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    A photochemical C=C cleavage process: toward access to backbone N-formyl peptides
    (Beilstein-Institut, 2021) Wang, Haopei; Ball, Zachary T.
    Photo-responsive modifications and photo-uncaging concepts are useful for spatiotemporal control of peptides structure and function. While side chain photo-responsive modifications are relatively common, access to photo-responsive modifications of backbone N–H bonds is quite limited. This letter describes a new photocleavage pathway, affording N-formyl amides from vinylogous nitroaryl precursors under physiologically relevant conditions via a formal oxidative C=C cleavage. The N-formyl amide products have unique properties and reactivity, but are difficult or impossible to access by traditional synthetic approaches.
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    Copper-mediated peptide arylation selective for the N-terminus
    (Royal Society of Chemistry, 2020) Miller, Mary K.; Wang, Haopei; Hanaya, Kengo; Zhang, Olivia; Berlaga, Alex; Ball, Zachary T.
    Polypeptides present remarkable selectivity challenges for chemical methods. Amino groups are ubiquitous in polypeptide structure, yet few paradigms exist for reactivity and selectivity in arylation of amine groups. This communication describes the utilization of boronic acid reagents bearing certain o-electron withdrawing groups for copper-mediated amine arylation of the N-terminus under mild conditions and primarily aqueous solvent. The method adds to the toolkit of boronic acid reagents for polypeptide modification under mild conditions in water that shows complete selectivity for the N-terminus in the presence of lysine side chains.
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    Studies of Cu-catalyzed installation and photochemical removal of peptide N-H modifications
    (2021-09-17) Wang, Haopei; Ball, Zachary T.
    Methods for selective modification of peptides are important for chemical biology and pharmaceutical industries. Among many reagents for modification, boronic acids have become a popular reaction partner for peptide under mild conditions. On the other hand, nitro aryl compounds have various roles in nature and industries. Its photosensitive properties lead to various photoreactions and applications as photo-labile protecting groups. This thesis has two main components: one component is about modification of peptides using boronic acids, and the other about the fate of nitro aryl moiety installed onto peptide using boronic acids. Chapter 1,4, and 5 belong to the first component. Chapter 1 is a review of peptide modification using boronic acids to form new C-C bond. Chapter 4 presents the development of a new method for peptide N-terminal modification using certain o-substituted boronic acids and copper (II) salts. The focus will be on method development for determining yield, and boronic acids scope screening. Chapter 5 will present an attempt of synthesizing peptide thioesters using histidine-directed peptide backbone arylation. Preliminary data with model peptides and potential future direction of the project will be discussed. Chapter 2 and 3 focus on nitro aryl compounds. Chapter 2 is a review about various photoreactions of nitro aryl compounds. Chapter 3 is a study of byproducts from photocleavage of nitroaromatic-containing peptide modification using small-molecule models. A bifurcating mechanism is proposed for reactions at different pH.