The objective of this thesis is to prepare new photochromic N,C-chelate four-coordinate organoboron compounds and investigate their photophysical and photochemical properties. Phenylpyridine-based organoboron compound (PhPyBMes2) was prepared and studied with NMR, X-ray, and UV-Vis. Experimental and theoretical results established that PhPyBMes2 is photochromic and the photoisomerization process involves a reversible intramolecular C-C bond formation/breaking. The structure of the dark colored isomer of PhPyBMes2 was established by 2D NMR experiments and computational studies. The discovery of the photochromic behavior of PhPyBMes2 led to the investigation of other phenylpyridine-based organoboron compounds. A series of substituted PhPyBMes2 compounds were synthesized with substituents on the phenyl ring or the pyridine ring of the N,C-chelate. Two other compounds were synthesized by substituting the mesityl rings in PhPyBMes2 with phenyl or pentaflurophenyl rings. The photophysical and photochemical properties of these compounds were studied by NMR, UV-Vis, and DFT/TD-DFT. The studies established that the steric hindrance imposed by the mesityl groups and the nature of substituents on the N,C-chelate have substantial effects on the photoisomerization process. New organoboron compounds based on N,C-chelates other than phenylpyridine were prepared and their photochemical and photophysical properties studied using NMR, UV-Vis, and DFT/TD-DFT. The phenyl group in the N,C-chelate was replaced by TMS-furan, TMS-thiophene, benzofuran, benzothiophene, and N-phenyl pyridylindole groups. The conducted studies show that these new compounds have photochromic properties similar to those of phenylpyridine-based compounds. Crystals of the dark isomer of the N-phenyl pyridylindole organoboron compound were successfully grown and the structure of the dark isomer was determined by X-ray diffraction. New organoboron compounds based on phenyl-benzoxazole and phenyl-benzothiazole have been also prepared and studied. The photoisomerization of these compounds is similar to the other N,C-chelate organoboron compounds but their thermal behavior is different. / Thesis (Ph.D, Chemistry) -- Queen's University, 2011-08-22 11:50:50.811

No description available.

A range of N-H alkynylaziridines were prepared from amphoteric unprotected aziridine aldehydes without protecting-group manipulation. Unprotected alpha -amino allenes can be obtained from these strained propargyl amines via a 9-BBN mediated hydride transfer. Further transformation of alpha -amino allenes to 2,4,6-trisubstituted pyridines was realized. We also developed another class of amphoteric molecules – alpha-boryl aldehydes, equipped with the tetrahedral MIDA boryl group. A wide range of boryl-substituted building blocks or functionalized boronic acid derivatives have been accessed from these bench-stable alpha-borylcarbonyl compounds. Further chemoselective transformations of these alpha-boryl aldehyde derived building blocks have been conducted, where alph-boryl isocyanates, alpha-aminoboronic acids, acylboronates, and borylated heterocycles were achieved through the decarboxylative functionalization of alpha-borylcarboxylic acids.

Thesis (Ph. D.)--University of Adelaide, 1989. / Includes bibliographical references (leaves 134-148).

Thesis (M.S.)--Rochester Institute of Technology, 1990. / Typescript. References: leaves 66-70.

Thesis (Ph. D.)--Texas Christian University, 2009. / Title from dissertation title page (viewed Apr. 19, 2010). Includes abstract. Includes bibliographical references.

I. Rhodium-Catalysed Carbometalation of Ynamides using Organoboron Reagents. As an expansion of existing procedures for the carbometalation of ynamides, it was discovered that [Rh(cod)(MeCN)2]BF4 successfully promotes the carbometalation of ynamides with organoboron reagents. A variety of organoboron reagents were found to be suitable for this reaction, but mostly the use of arylboronic acids was explored. The developed methodology provides β,β-disubstituted enamide products in a regio- and stereocontrolled manner. II. Palladium-Catalysed Hydroacyloxylation of Ynamides. In the presence of palladium(II) acetate, ynamides successfully underwent a hydroacyloxylation reaction with a variety of carboxylic acids. This carboxylic acid addition occurred highly regio- and stereoselectively to provide α-acyloxyenamides. Applications of the α-acyloxyenamide products were also investigated. III. Rhodium-Catalysed [2+2] Cycloaddition of Ynamides with Nitroalkenes. A novel rhodium catalyst system has been developed in order to promote the [2+2] cycloaddition reaction between ynamides and nitroalkenes. The reaction provides cyclobutenamide products and was diastereoselective in favour of the trans cyclobutenamide. Both the ynamide scope and the nitroalkene scope of the reaction have been explored.

He, Xiao. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2011. / Includes bibliographical references (leaves 75-83). / Abstracts in English and Chinese. / Acknowledgement --- p.I / Abstract --- p.II / 摘要 --- p.III / Abbreviation --- p.IV / List of Compounds --- p.VI / List of Figures --- p.VII / Contents --- p.IX / Chapter Chapter 1 --- Introduction --- p.1 / Chapter 1.1 --- Transition Metal-Carboranyl Complexes --- p.2 / Chapter 1.1.1 --- Late Transition Metal-Carboranyl Complexes --- p.2 / Chapter 1.1.2 --- Early Transition Metal-Carboranyl Complexes --- p.6 / Chapter 1.2 --- Transition Metal-Carboryne Complexes --- p.12 / Chapter 1.3 --- Five-Membered Heterocycles Incorporating Main Group Elements --- p.20 / Chapter 1.3.1 --- Synthesis and Reactivity of Boroles --- p.20 / Chapter 1.3.2 --- Synthesis and Reactivity of Phospholes --- p.24 / Chapter 1.3.3 --- Synthsis and Reactivity of Silole --- p.28 / Chapter 1.4 --- Our Objectives --- p.31 / Chapter Chapter 2 --- Nickelacycles Incorporating a Carboranyl Unit --- p.32 / Chapter 2.1 --- Introduction --- p.32 / Chapter 2.2 --- "Synthesis, Characterization and Reactivity of Nickelacycles Bearing (2-CPh2O-l,2-C2B10H10)2-Ligand" --- p.32 / Chapter 2.2.1 --- Synthesis and Characterization --- p.32 / Chapter 2.2.2 --- Reactivity Study --- p.34 / Chapter 2.2.3 --- X-ray Structure --- p.36 / Chapter 2.3 --- "Synthesis and Characterization of Nickelacycles Bearing [2-C(Ph)=N-l,2-C2B10H10]2- Ligand" --- p.44 / Chapter 2.3.1 --- Synthesis and Characterization --- p.44 / Chapter 2.3.2 --- X-ray Structure --- p.45 / Chapter Chapter 3 --- Five-membered Heterocycles of Main Group Elements Incorporating a Carboranyl Unit --- p.47 / Chapter 3.1 --- Synthesis and Characterization of Heterocycles Bearing Phosphorus Element --- p.47 / Chapter 3.2 --- Synthesis and Characterization of Heterocycles Bearing Silicon Element --- p.53 / Chapter 3.3 --- Synthesis and Characterization Heterocycles Bearing Boron Element --- p.58 / Chapter Chapter 4 --- Conclusion --- p.61 / Chapter Chapter 5 --- Experimental Section --- p.63 / References --- p.75 / Appendix --- p.84 / Chapter I. --- Crystal Data and Summary of Data Collection and Refinement --- p.84 / Chapter II. --- X-ray crystallographic data in CIF (electronic form)

There has been increasing interest in the syntheses of carbohydrates due to their profound role in various biological processes and thus their potential in drug development. Various methods have been developed for the preparation of these oligosaccharides from simpler carbohydrate derivatives both chemically and enzymatically but they must be carefully applied to obtain the desired linkages. The main method that has been used to control the regioselectivity of glycosylations is protecting group chemistry. Unfortunately this requires additional steps lengthening the synthesis sequence. Extensive literature has shown the ability for carbohydrate recognition via organoboron methods through selective binding and their ability to undergo regioselective glycosylation through sugar-derived boronate esters. Exploiting these factors and in extension of previous work done in our laboratory on borinic acid- and boronic acid-catalyzed regioselective glycosylations of carbohydrate derivatives, we proposed a target oriented synthesis of a pentassacharide moiety found in four saponins isolated from Spergularia ramosa.

There has been increasing interest in the syntheses of carbohydrates due to their profound role in various biological processes and thus their potential in drug development. Various methods have been developed for the preparation of these oligosaccharides from simpler carbohydrate derivatives both chemically and enzymatically but they must be carefully applied to obtain the desired linkages. The main method that has been used to control the regioselectivity of glycosylations is protecting group chemistry. Unfortunately this requires additional steps lengthening the synthesis sequence. Extensive literature has shown the ability for carbohydrate recognition via organoboron methods through selective binding and their ability to undergo regioselective glycosylation through sugar-derived boronate esters. Exploiting these factors and in extension of previous work done in our laboratory on borinic acid- and boronic acid-catalyzed regioselective glycosylations of carbohydrate derivatives, we proposed a target oriented synthesis of a pentassacharide moiety found in four saponins isolated from Spergularia ramosa.