Applications of Alkynogenic Fragmentation Products Derived from Vinylogous Acyl Triflates

Carbon-carbon bond formation is the foundation to synthesizing complex molecules and has gathered the attention of many synthetic chemists. One must keep in mind that these reactions are dependent on materials for a specific agenda when tackling a structural framework, which may require additional steps to create, and at times, are difficult to prepare. As significant as C-C bond formation reactions are, these minor setbacks may draw caution when synthesizing a complicated molecule whose structural framework cannot be easily accessed by the unity of two fragments. On the other hand, the less familiar C-C bond cleavage reactions have, over time, demonstrated the potential to generate unique structural building blocks that can be used to overcome certain obstacles that other synthetic methods cannot provide. Here, we will be focusing on concerted anionic five-center fragmentation reactions using vinylogous acyl triflates. The generated alkynogenic fragments will then be used in different applications. We will begin by looking at chemoselective “click” reactions. The strained-promoted alkyne is synthesized by a tandem intramolecular nucleophilic addition / fragmentation. The expanded ring will contain a strained cycloalkyne which will later be tethered to a terminal alkyne. The diyne will be used to provide an example of a “dual-click” coupling via SPAAC or CuAAC in either sequential order. Next, we will expand the tandem fragmentation / olefination methodology developed in this work to include dienynes. The dienyne provides the structural backbone needed to produce neopentylene indanes. This methodology is used to design new ibuprofen derivatives that demonstrate rigidity and increase hydrophobicity to modulate the molecular pharmacology of ibuprofen.