The use of coordinating moieties as directing groups for the functionalization of aromatic CH bonds has become an established tool to enhance reactivity and induce regioselectivity. Nevertheless, with regard to the synthetic applicability of CH activation, there is a growing interest in transformations in which the directing group can be fully abandoned, thus allowing the direct functionalization of simple benzene derivatives. However, this approach requires the disclosure of new strategies to achieve reactivity and to control selectivity. In this review, recent advances in the emerging field of non-chelate-assisted CH activation are discussed, highlighting some of the most intriguing and inspiring examples of induction of reactivity and selectivity.

Beyond directing groups: transition-metal-catalyzed C-H activation of simple arenes.

Complete Field Guide to Asymmetric BINOL-Phosphate Derived Brønsted Acid and Metal Catalysis: History and Classification by Mode of Activation; Brønsted Acidity, Hydrogen Bonding, Ion Pairing, and Metal Phosphates

The combination of transition metal catalysis and organocatalysis as a new and exciting research area has attracted increasing attention as it can enable the development of unprecedented transformations that is not possible by use of either of the catalytic systems alone, and can improve the reactivity, efficiency and stereocontrol of existing chemical transformations. In this review, we summarize recent remarkable progress in the field of combined transition metal catalysis and organocatalysis, further highlighting the potential of this new and exciting research area and the many challenges that still remain for the future.

Combining transition metal catalysis and organocatalysis--an update.

Since about the year 2000, the research area of asymmetric organocatalysis has grown rapidly to become one of the most fascinating and current fields in organic chemistry. In the last years, asymmetric domino reactions have widely benefited from this fast-growing field, as exemplified by the development of an explosive number of novel and powerful asymmetric organocatalytic domino processes, which allowed the easy construction of complex chiral molecular architectures from simple materials with high yields and very often remarkable enantioselectivities in a metal-free environment. Indeed, the possibility to join two or more organocatalytic reactions in one asymmetric domino process has become a challenging goal for chemists, due to several advantages from economical and environmental points of view, avoiding costly protecting groups and time-consuming purification procedures after each step, for example. This review aims to update the latest developments of this hot and fascinating field, covering the literature since the beginning of 2009. 

Abbreviations: Ac: acetyl; Ar: aryl; BDHP: 1,1′-binaphth-2,2′-diyl hydrogen phosphate; BA: Bronsted acid; BINAPO: 2-diphenylphosphino-2′-diphenylphosphinyl-1,1′-binaphthalene; BINOL: 1,1′-bi-2-naphthol; Boc: tert-butoxycarbonyl; Bn: benzyl; Bu: butyl; Bz: benzoyl; CSA: camphorsulfonic acid; Cy: cyclohexyl; Cbz: benzyloxycarbonyl; DABCO: 1,4-diazabicyclo[2.2.2]octane; DBU: 1,8-diazabicyclo[5.4.0]undec-7-ene; DCE: dichloroethane; de: diastereomeric excess; DFT: density functional theory; DHQ: hydroquinine; DHQD: dihydroquinidine; DIPEA: diisopropylethylamine; DKR: dynamic kinetic resolution; DMAD: dimethyl acetylenedicarboxylate; E: electrophile; ee: enantiomeric excess; ESI: electrospray ionization; Et: ethyl; Fu: furyl; Hept: heptyl; Hex: hexyl; HOMO: highest occupied molecular orbital; IBX: o-iodoxybenzoic acid; LB: Lewis base; LUMO: lowest unoccupied molecular orbital; Me: methyl; MOM: methoxymethyl; Mes: mesyl; MS: mass spectroscopy; MTBE: methyl tert-butyl ether; NADH: nicotinamide adenine dinucleotide; Naph: naphthyl; NHC: N-heterocyclic carbene; NMM: N-methylmorpholine; NMP: N-methylpyrrolidinone; Ns: nosyl; Nu: nucleophile; Oct: octyl; PCC: pyridinium chlorochromate; Pent: pentyl; PFBA: pentafluorobenzoic acid; Ph: phenyl; PMB: para-methoxybenzyl; Pr: propyl; Py: pyridine; r.t.: room temperature; TBA: tribromoacetic acid; TBS: tert-butyldimethylsilyl; TCBA: 2,4,6-trichlorobenzoic acid; TES: triethylsilyl; TFA: trifluoroacetic acid; THF: tetrahydrofuran; Thio: thiophene; TMEDA: tetramethylethylenediamine; TMS: trimethylsilyl; Tol: tolyl; Ts: 4-toluenesulfonyl (tosyl).

Recent Developments in Asymmetric Organocatalytic Domino Reactions

Chiral phosphoric acids and derivatives have attracted considerable attention as a powerful tool in asymmetric catalysis. Various enantioselective reactions have been developed by using these efficient Bronsted acid organocatalysts. Although initially the activation was restricted to reactive Bronsted basic substrates, recent reports are demonstrating the versatility of phosphoric acid catalysts in the activation of carbonyl compounds in a stereochemically controlled fashion. This tutorial review gives an overview of enantioselective Bronsted acid catalyzed transformations with the main focus on carbonyl activation. Different activation modes, key features of the catalysts and the applied substrates are presented and discussed with the goal to elucidate the origin of stereoselectivity in these Bronsted acid catalyzed transformations.

Chiral Brønsted acids in enantioselective carbonyl activations – activation modes and applications

The asymmetric Friedel–Crafts reaction is one of the most powerful methods to synthesize optically active aromatic compounds. Particularly, the Friedel–Crafts alkylation of arenes with unsaturated compounds activated by chiral Bronsted acids provides direct access to enantiopure aromatic derivatives with perfect atom economy. In this tutorial review, recent progress in the development of chiral Bronsted acid-catalyzed asymmetric Friedel–Crafts reactions is presented.

Mi Zeng

Papers

Chiral Bronsted acid catalyzed Friedel-Crafts alkylation reactions

Chiral Broensted Acid Catalyzed Friedel—Crafts Alkylation Reactions