Catalytic electrophilic halogenation of silyl-protected and terminal alkynes: trapping gold(I) acetylides vs. a bronsted acid-promoted reaction

In the presence of a cationic gold(I) catalyst and N-halosuccinimide, both trimethylsilyl-protected and terminal alkynes are converted into alkynyl halides. Further experiments showed that silyl-protected alkynes undergo electrophilic iodination and bromination under Brønsted acid catalysis, whilst terminal alkynes require a cationic gold catalyst. The former reactions probably proceed via activation of the electrophile, whilst the latter reactions proceed via a gold(I) acetylide intermediate. Gold-catalysed halogenation was further combined with gold-catalysed hydration and subsequent annulation to provide convenient routes to iodomethyl ketones and five-membered aromatic heterocycles

Catalyst-free spontaneous polymerization with 100% atom economy: facile synthesis of photoresponsive polysulfonates with multifunctionalities

Photoresponsive polymers have attracted extensive attention due to their tunable functionalities and advanced applications; thus, it is significant to develop facile in situ synthesis strategies, extend polymers family, and establish various applications for photoresponsive polymers. Herein, we develop a catalyst-free spontaneous polymerization of dihaloalkynes and disulfonic acids without photosensitive monomers for the in situ synthesis of photoresponsive polysulfonates at room temperature in air with 100% atom economy in high yields. The resulting polysulfonates could undergo visible photodegradation with strong photoacid generation, leading to various applications including dual-emissive or 3D photopatterning, and practical broad-spectrum antibacterial activity. The halogen-rich polysulfonates also exhibit a high and photoswitched refractive index and could undergo efficient postfunctionalizations to further expand the variety and functionality of photoresponsive heteroatom-containing polyesters

Synthetic utility and reactivity of N-alkynylazoles

textThe chemistry of N-alkynylazoles is a newly emerging area of chemistry with particular interest in heterocycle synthesis. Synthetic preparations of this class of molecule have shown an increasing presence in literature, however, the synthetic utility of this class of molecule remains underexplored. Herein, it is shown that N-alkynlazoles are a versatile synthetic intermediate and may have utility as covalent modifiers of cysteine residues in polypeptides.Pharmaceutical Science

Expanding the scope of alkyne-mediated bioconjugations utilizing unnatural amino acids

The importance of bioconjugates within the field of chemistry drives the need for novelmethodologies for their preparation. Well-defined and stable bioconjugates are easily accessible via the utilization of unnatural amino acids (UAAs). As such, we have synthesized and incorporated two new UAAs into green fluorescent protein, and optimized a novel Cadiot-Chodkiewicz bioconjugation, effectively expanding the toolbox of chemical reactions that can be employed in the preparation of bioconjugates

Unsaturated Organosulfur Chemistry: synthesis and applications

The original focus of this thesis was ynol ether synthesis which was successful using simple and easy-to-prepare precursors (chloroacetylenes) but low yielding. Attention was then diverted to the design and synthesis of a range of thioynol ethers (alkynyl sulfides) utilising chloroacetylenes. The reaction of a chloroacetylene with a thiolate salt in the presence of an amine mediator (Me2NH or DMEDA) yielded the alkynyl sulfides in excellent yields. The alkynyl chlorides were easily prepared from the parent alkynes contrasting sharply with the cumbersome synthesis of an alkynyl sulfonamide previously required. As well as chloroacetylenes, bromo- and iodoacetylenes have also been studied and the differences in their reactivity are highlighted. With a successful route to thioynol ethers at hand, brief mechanistic investigations were conducted into their reactivity. Finally, preliminary studies have been carried out on the reactivity of their derivatives

Preparation of some alkynes and alkenynes

The following thesis concerns the preparation of several alkynes and their conversion to alkenynes. Alkynes are of interest because of their potential biological activity (1), general reactivity to boranes (2), complexing ability with some transition metals (3), as well as other general reactions of π bonds (4). It was the intention of this investigation to prepare several alkynes with varying degrees of steric hindrance and evaluate the effect of this property. Double bonds were incorporated in several of these compounds to aid in the assessment

The Divalent Titanium Complex Ti(O-i-Pr)4/2i-PrMgX as an Efficient and Practical Reagent for Fine Chemical Synthesis

New efficient and sophisticated reagents and reac-tions for organic synthesis are being developed more and more rapidly each year. Owing to these develop-ments, modern organic synthesis has reached such