Asymmetric Catalysis with Chiral Frustrated Lewis Pairs

Abstract

The chemistry of frustrated Lewis pairs (FLPs) provides the most important approach for the metal-free hydrogenation and hydrosilylations. Great progress has been achieved in this area for the past decade. Some promising results have also been obtained. This perspective article mainly focuses on the recent advances for the synthesis of chiral Lewis acidic boranes in category of three protocols, 1) hydroboration of chiral internal alkenes with Piers' borane HB(C6F5)2; 2) in situ hydroboration of chiral alkenes or alkynes without any purification; 3) and substitution reaction of (C6F5)nBCl3-n with chiral organometallic reagents, as well as their applications in the metal-free asymmetric hydrogenations and hydrosilylations.

Isospecific Polymerization of Methyl Methacrylate by Intramolecular Rare‐Earth Metal Based Lewis Pairs†

“…[ 2‐3 ] FLPs typically comprise sterically bulky main group Lewis acids and bases and can react with a large number of small molecules via synergistic acid/base interactions. [ 4 ] This has led to the applications of FLPs in various organic syntheses, such as hydrogenation, [ 5 ] hydroamination, [6] and C—H functionalization. [7] Notably, FLPs can also be used in the field of polymer synthesis.…”

Towards the Development of Frustrated Lewis Pair (FLP) Catalyzed Hydrogenations of Tertiary and Secondary Carboxylic Amides

“…The activation of small molecules by frustrated Lewis pairs (FLPs) [1][2][3] has evolved to a rapidly expanding field in chemistry covering new concepts in catalysis by main group element molecules. [4][5][6][7][8][9] Milestones 1-3 in this chemistry are certainly the development of highly active intramolecular FLPs, [10][11][12] asymmetric hydrogenations, 11,[13][14][15] olefin 16 and alkyne 17,18 hydrogenation, and the hydrogenation of ketones. [19][20][21] Amongst recent developments (e.g., C-H bond activations, [22][23][24][25][26][27] acceptorless dehydrogenations, [28][29][30] or metal-free cross-couplings 22,31,32 ), hydrogenation is still the most utilized and intensively investigated reaction of FLPs.…”

[B–Cl–B]+ Cations: Chloroborane Masked Chiral Borenium Ions

“…However, because of the low abundance and inherent toxicity of transition metals, considerable efforts have been shifted to the environmentally benign and sustainable alternatives that feature earth-abundant, nontoxic s- and p-block elements . Organocatalysts with Lewis acidic tricoordinate boron atoms embedded in chiral molecular frameworks derived from prolinol, camphor, and 1,1′-binaphthyl are especially attractive and have been extensively investigated . In addition to neutral boranes, chiral boron cations have also been examined for asymmetric catalysis. − Among them, in Chart , the chiral oxazaborolidinium ion ( A ) is the most explored system for its superb stereocontrol in asymmetric cyanosilylation of aldehyde and ketone, , Diels–Alder cycloaddition reaction, − Michael addition, Morita–Baylis–Hillman reaction, Mukaiyama aldol reaction, cyclopropanation, Roskamp reaction, Strecker reaction, and allylation reaction .…”