Key words
frustrated Lewis pairs - boron - phosphine - nitrogen - hydrogenation - C–C bonds - C–N bonds
Since the seminal report by Douglas Stephan[1a] reporting the reversible heterolytic splitting of molecular H2 by an intramolecular Lewis acid/Lewis base pair, the field of so-called frustrated Lewis pairs (FLP)[1b]
[1c] has evolved into one of the key research pillars in main group chemistry. A frustrated Lewis pair (FLP) consists of an electron-pair acceptor (Lewis acid) and an electron-pair donor (Lewis base) that cannot form a Lewis acid–base adduct because of steric reasons, thus leaving the individual reactivities available for synergistic activation with small molecules, e.g., hydrogen, carbon dioxide or nitrogen oxides.[1d] The activation of H2 is certainly one of the most important applications of FLP catalysts.[1`]
[f]
[g]
[h]
[i]
[j] However, new applications of FLP catalysts beyond hydrogenations have also been elaborated, e.g., hydroaminations, oxidations and cycloisomerizations.[1`]
[l]
[m] This Graphical Review provides a general overview of the development of FLP-catalyzed reactions with a focus on initial findings and recent achievements.
Rundong Zhou (left) was born in Shandong, P. R. of China. She earned her B.Sc. and M.Sc. degrees from Paderborn University (Germany). In 2019, she began her Ph.D. research at Paderborn University under the guidance of Prof. Dr. Jan Paradies. Her research is focused on frustrated Lewis pair catalyzed hydrogenations.
Zoleykha Pirhadi Tavandashti (center) was born in Borojerd, Iran. She received her M.Sc. in inorganic chemistry from Isfahan University of Technology (IUT) (Iran) in September 2018. In October 2021, she joined the group of Prof. Dr. Jan Paradies and started her Ph.D. research in the Department of Chemistry at Paderborn University. Her research is focused on asymmetric hydrogenations catalyzed by chiral boranes.
Jan Paradies (right) was born in Berlin and studied chemistry at the University of Münster and the University of Edinburgh. He received his diploma in chemistry in 2002 and joined the group of Prof. Dr. G. Erker at the University of Münster for his Ph.D. on the topic of photochemical reactions of organometallic compounds. After graduation in 2006, he joined the group of Prof. Dr. G. C. Fu at the Massachusetts Institute of Technology (MIT) as a DAAD postdoctoral fellow. In 2007, he started his independent career as a Liebig Fellow at the Karlsruhe Institute of Technology (KIT) under the mentorship of Prof. Dr. S. Bräse. After his habilitation in 2013 as a Heisenberg Fellow, he was appointed as a professor of organic chemistry at Paderborn University. His research is directed towards sulfur-rich heteroacenes and the exploration of frustrated Lewis pair chemistry.
Figure 1 Structure and reactivity of frustrated Lewis Pairs
Figure 2 Frustrated Lewis pair catalaysed hydrogenations of a) imines, b) enamines, c) heterocycles, d) nitriles and e) aziridines
Figure 3 Frustrated Lewis pair catalaysed hydrogenations of f) ketones g) olefins h) electron-deficient olefins i) aza-morita-Hilman adducts and j) alkynes and frustrated Lewis pair catalaysed asymmetric hydrogenations
Figure 4 Frustrated Lewis pair catalaysed asymmetric hydrogenation of c) quinoxalines d) carbonyls and transfer hydrogenations
Figure 5 Frustrated Lewis pair catalaysed C-C bond formation by a) cycloisomerizations b) Mannich-type reactions c) rearrangements d) Diels–Alder reactions and e) C–C couplings
Figure 6 Frustrated Lewis pair catalysed C–C and C–N bond formations
Figure 7 Frustrated Lewis pair catalysed C–Hal bond activations and defunctionalizations by a) deoxygenation of alcohols, ketones and esters, b) hydrodesulfurization, c) dehydrogenations and d) deoxygenations of phosphane oxides
Figure 8 Frustrated Lewis pair reductive defunctionalizations of e) amides, f) amines, g) nitriles and frustrated Lewis pair catalaysed C–H bond activations
Figure 9 Application of moisture-tolerant frustrated Lewis pairs
