Base–Metal‐Catalyzed Regiodivergent Alkene Hydrosilylations

Abstract

A complementary set of base metal catalysts has been developed for regiodivergent alkene hydrosilylations: iron complexes of phosphine-iminopyridine are selective for anti-Markovnikov hydrosilylations (linear/branched up to >99:1), while the cobalt complexes bearing the same type of ligands provide an unprecedented high level of Markovnikov selectivity (branched/linear up to >99:1). Both systems exhibit high efficiency and wide functional group tolerance.

Iron Catalysis in Organic Synthesis: A Critical Assessment of What It Takes To Make This Base Metal a Multitasking Champion

“…35−38 Therefore, it is hardly surprising that related ligands have already served various types of transformations well. 39−42 Even the ubiquitous CO or isonitrile ligands can “iron out” changes in charge density at the central metal, at least to some degree.…”

Recent Developments in the Photo‐Mediated Generation of Silyl Radicals and Their Application in Organic Synthesis

“…Speier and Karstedt have demonstrated the use of platinum catalysts for direct Si‐H bond activation in hydrosilylation, and has been employed in industrial‐scale manufacturing . Intensive research in hydrosilylation have led to the discovery of other effective catalysts such as earth‐abundant Fe, Ni, and Co metals . In addition, recent advancement demonstrated the metal‐free hydrosilylation using electron‐deficient borane Lewis acid catalysts …”

“…[34] Intensive research in hydrosilylation have led to the discovery of other effective catalysts such as earth-abundant Fe, Ni, and Co metals. [35][36][37][38][39][40][41][42] In addition, recent advancement demonstrated the metal-free hydrosilylation using electron-deficient borane Lewis acid catalysts. [43] In 2015, Fagnoni, Ravelli, and co-workers disclosed an elegant hydrosilylation of electron-deficient alkenes through the use of tetrabutylammonium decatungstate (TBADT, (nBu 4 N) 4 -[W 10 O 32 ]) as a direct HAT photocatalyst under UV light (310 nm) irradiation.…”

Cobalt‐Catalyzed Regio‐ and Stereoselective Hydroboration of Allenes

“…Based on the pincer ligand-based iron and cobalt complexes developed in Huangs group, [12] initially, ( tBu P O NN iPr )FeCl 2 (1) was chosen as the precatalyst for the hydroboration of 1,2-undecadiene (3 a) with HBpin in toluene. Unfortunately, only a complicated mixture was formed.…”

“…Unfortunately, only a complicated mixture was formed. Subsequently, a series of complexes of Fe and Co supported by various P C NN ligands [12] were investigated. To our delight, by using ( tBu P C NN iPr )FeCl 2 (2 a) as the precatalyst, the reaction afforded Z-4 a in a high yield together with small amounts of regioisomers 5 a and 6 a as determined by 1 H NMR analysis of the crude reaction mixture (Table 1, entry 2).…”