Organic Transformations Utilizing 1,5,7‐Triazabicyclo[4.4.0]dec‐5‐ene (TBD): A Tale of Two Nitrogens

1,5,7‐Triazabicyclo[4.4.0]dec‐5‐ene (TBD) is a bicyclic guanidine with booming applications. Bearing both a nucleophilic nitrogen and an electrophilic nitrogen, TBD is a multifunctional and versatile reagent that is able to promote a variety of organic transformations. Although advancements with TBD in the polymer field have been well reviewed and documented, summaries that focus on synthetic methodologies are scarce. This review intends to provide a concise overview of synthetic methods utilizing TBD published over the past two decades. Classified based on the primary function of TBD, diverse transformations are described, and reaction mechanisms are incorporated when necessary. Examples from various fields are covered, including methodology developments, natural product syntheses, medicinal chemistry applications, as well as industrial utilizations.