|Title||Titanium catalyzed synthesis of amines and N-heterocycles|
|Publication Type||Book Chapter|
|Year of Publication||2020|
|Authors||Schafer, LL, Manßen, M, Edwards, PM, Lui, EKJ, Griffin, SE, Dunbar, CR|
|Book Title||Advances in Organometallic Chemistry|
|Keywords||Green chemistry, HYDROAMINATION, HYDROAMINOALKYLATION, Hydrofunctionalization, Multicomponent coupling, One-pot reactions, Redox-relay reactions, Reductive coupling|
Titanium is an earth abundant inexpensive early transition metal that has been used extensively in industrial polyolefin synthesis, but rarely applied toward the synthesis of fine chemicals. Recent advances have shown the usefulness of titanium catalyzed reactions in the catalytic synthesis of amines and N-heterocycles by both hydroamination and hydroaminoalkylation. These atom economic transformations can be coupled with other reactive bond insertion processes to realize catalytic multicomponent coupling reactions to generate more complex products. Alternatively, sequential catalytic protocols can be accomplished in one-pot to achieve efficient transformations, further emphasizing titanium catalysis as an under-utilized metal for Green Chemistry. Titanium also has multiple oxidation states that are accessible and have been featured in stoichiometric reactions over the past 40 years. More recently new strategies for taking advantage of oxidative addition/reductive elimination protocols and radical chemistry has resulted in new catalytic approaches. Throughout the highlighted work titanium offers complementary reactivity to established late transition metal protocols. However, ligand modified reactivity remains poorly understood and the development of predictive tools for understanding how ligands influence electronic properties at the metal center will advance efforts to realize new catalytic reactions. Furthermore, strategic ligand designs that control the steric environment about the titanium metal center to promote stereoselective transformations are desirable. Due to the extensive exploration of fundamental stoichiometric transformations with titanium complexes over the years, there are many attractive reactions that await creative insights for the realization of catalytic variants.