Boron-Mediated Methodologies for Carbon-Oxygen, Carbon-Hydrogen Bond Breaking and Carbon-Nitrogen, Carbon-Carbon Bond Formation

• Author / Creator

  Truong, Nam VH

• Boron Lewis acids are a class of reagent that has been widely studied and utilized in organic chemistry for over sixty years. The popularity of these reagents comes from their diverse reactivity, functional group tolerance, and non-toxic nature. For these reasons, the continued development of chemistries involving boron reagents still receives much attention. This thesis examines the development of new methodologies for the functionalization of organic molecules based on boron reagents.
  Chapter 1 briefly describes general methodologies to synthesize azide compounds. Later, the mechanisms of photochemical decomposition of various azides will be discussed.
  Borontribromide-mediated dissociation of carbon-oxygen bonds has been extensively used to cleave aryl ethers. However, the regioselectivity is low when applying this method to unsymmetrical dialkyl ethers. The second chapter of this thesis describes the cleavage of unsymmetrical dialkyl ethers employing mixed boron trihalides. The selectivity profile of this new methodology is evaluated on various ether substrates, including benzyl, allyl, and propargyl ethers.
  Nitrenes are a high energy, reactive specie generated from thermolysis or photolysis of an azide precursor. Recently, it has been demonstrated that boryl nitrenes can insert into C−H bonds of unreactive substrates such as alkanes. The third chapter describes a one-pot three-step procedure to generate amino alcohols from simple or complex alcohols utilizing a boryl azide precursor. Using mixed boron halides, as described in chapter 2, many dialkoxyboryl chlorides were prepared and subsequently converted to the dialkoxyboryl azide. Chapter 3 describes the investigation of the photochemical decomposition of these azides.
  The Suzuki-Miyaura reaction is a versatile and powerful synthetic method to construct C−C bonds using aryl boronic acids. However, the application of this method in modification of biomolecule substrates is limited due to the instability of many biological molecules such as proteins in the presence of bases and high temperature. Chapter 4 will discuss the synthesis of new N-heterocyclic carbenes ligands to facilitate the Suzuki cross-coupling reaction in aqueous media in the absence of bases and elevated temperature.

• Subjects / Keywords

  • photochemistry
  • Boron chemistry
  • ether cleavage

• Graduation date

  Fall 2019

• Type of Item

  Thesis

• Degree

  Master of Science

• DOI

  https://doi.org/10.7939/r3-y9yt-xf30

• License

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