In this minireview we present the use of the axially chiral 1,1'-binaphthyl-2,2'-diol (BINOL) unit as a stereogenic element in mechanically interlocked molecules (MIMs). We describe the synthesis and properties of such BINOL-based chiral MIMs, together with their use in further diastereoselective modifications, their application in asymmetric catalysis, and their use in stereoselective chemosensing. Given the growing importance of mechanically interlocked molecules and the key advantages of the privileged chiral BINOL backbone, we believe that this research area will continue to grow and deliver many useful applications in the future. © 2022 Krajnc and Niemeyer.

The linking of phosphoric acids via covalent or mechanical bonds has proven to be a successful strategy for the design of novel organocatalysts. Here, we present the first systematic investigation of singly-linked and macrocyclic bisphosphoric acids, including their synthesis and their application in phase-transfer and Brønsted acid catalysis. We found that the novel bisphosphoric acids show dramatically increased enantioselectivities in comparison to their monophosphoric acid analogues. However, the nature, length and number of linkers has a profound influence on the enantioselectivities. In the asymmetric dearomative fluorination via phase-transfer catalysis, bisphosphoric acids with a single, rigid bisalkyne-linker give the best results with moderate to good enantiomeric excesses. In contrast, bisphosphoric acids with flexible linkers give excellent enantioselectivities in the transfer-hydrogenation of quinolines via cooperative Brønsted acid catalysis. In the latter case, sufficiently long linkers are needed for high stereoselectivities, as found experimentally and supported by DFT calculations. © 2022 The Authors. Chemistry - A European Journal published by Wiley-VCH GmbH.

Transformation of [15]paracyclophanes ([15]PCP) into fluorophores has been achieved by embedding tetraphenylethene (TPE) units into their skeletons at the meso-positions. The obtained two hosts demonstrated distinct aggregation-induced emission (AIE) properties and their fluorescence could be selectively quenched by Ni2+ ions. © 2022 The Royal Society of Chemistry

A double-helical supramolecular structure was formed by self-assembly of 1,1′-binaphthyl-based bisguanidines and bisphosphoric acids. Interestingly the homochiral (S,S) + (S,S)-pair forms a left-handed double-helix, while the heterochiral (S,S) + (R,R)-pair forms a non-helical dimer. © The Royal Society of Chemistry.

In this account, we describe the application of a series of multidentate BINOL-based phosphoric acids for the fluorescence-based chemosensing of amino sugars. To this end, we developed a novel synthetic protocol for three isomerically pure phosphoric acid monoesters of the type ArOP(O)(OH)2. These were investigated with respect to their binding towards amino sugars (glucosamine, galactosamine and mannosamine) in comparison to the previously reported diesters of the type (ArO)2P(O)(OH). We could find that the diesters show no significant binding, while the monoesters can be used as hosts for amino sugars. Indeed, one host selectively binds to galactosamine, while a second host binds both glucosamine and mannosamine. This allows the fluorescence-based detection and discrimination of the amino sugars by a novel class of phosphate-based supramolecular hosts. © 2021 The Authors. Israel Journal of Chemistry published by Wiley-VCH GmbH

Mechanically interlocked molecules (MIMs) have gained attention in the field of catalysis due to their unique molecular properties. Central to MIMs, rotaxanes are highly promising and attractive supramolecular catalysts due to their unique three-dimensional structures and the flexibility of their subcomponents. This Minireview discusses the use of rotaxanes in organocatalysis and transition-metal catalysis. © 2020 The Authors. Published by Wiley-VCH GmbH

The self-assembly of bifunctional photoredoxcatalysts is reported. A series of photosensitizers and water-reducing catalysts were functionalized with viologen- and naphthol-units, respectively. Subsequent formation of the heteroternary cucurbit[8]uril-viologen-naphthol complexes was used for the constitution of bifunctional photoredoxcatalysts for hydrogen generation. © The Royal Society of Chemistry 2021.

Mechanically interlocked molecules (MIMs) carry great potential in different fields of chemistry, based on their specific structures, their internal dynamics, their stimuli-responsive behavior, and other unique features of the mechanical bond. This minireview presents some of the most recent developments in their use for medical and biological applications. For example, they have been used to influence, enhance or block the action of therapeutic agents to enable targeted drug delivery. The dynamic structural properties have been used to generate switches and transporters, as well as sensors for various medically relevant species. Building MIMs by incorporating biomolecules like DNA and proteins has served as a novel way to control their properties. © 2021 The Authors. European Journal of Organic Chemistry published by Wiley-VCH GmbH

A series of reactive binaphthyl-diimine-based dopants is prepared and investigated with respect to their potential for the chiral induction of structural coloration in nematic liquid crystal mixture E7 and the selective photonic sensing of nitrogen dioxide (NO2). Studies of the helical twisting power (HTP) in 4-cyano-4′-pentylbiphenyl (5CB) reveal HTP values as high as 375 µm-1 and the tremendous impact of structural compatibility and changes of the dihedral binaphthyl angle on the efficiency of the chiral transfer. Detailed investigation of the sensing capabilities of the systems reveals an extraordinarily high selectivity for NO2 and a response to concentrations as low as 100 ppm. The systems show a direct response to the analyte gas leading to a concentration-dependent shift of the reflectance wavelength of up to several hundred nanometers. Incorporation of copper ions remarkably improves the sensor's properties in terms of sensitivity and selectivity, enabling the tailored tweaking of the system's properties. © 2021 The Authors. Advanced Optical Materials published by Wiley-VCH GmbH

We report a pH- and temperature-controlled reversible self-assembly of Au-nanoparticles (AuNPs) in water, based on their surface modification with cationic guanidiniocarbonyl pyrrole (GCP) and zwitterionic guanidiniocarbonyl pyrrole carboxylate (GCPZ) binding motifs. When both binding motifs are installed in a carefully balanced ratio, the resulting functionalized AuNPs self-assemble at pH 1, pH 7 and pH 13, whereas they disassemble at pH 3 and pH 11. Further disassembly can be achieved at elevated temperatures at pH 1 and pH 13. Thus, we were able to prepare functionalized nanoparticles that can be assembled/disassembled in seven alternating regimes, simply controlled by pH and temperature. © 2021 The Authors. Chemistry - A European Journal published by Wiley-VCH GmbH

We report novel supramolecular polymers, which possess a reversed viscosity/temperature profile. To this end, we developed a series of ditopic monomers featuring two self-complementary binding sites, either the guanidiniocarbonyl pyrrole carboxylic acid (GCP) or the aminopyridine carbonyl pyrrole carboxylic acid (ACP). At low temperatures, small cyclic structures are formed. However, at elevated temperatures, a ring–chain transformation leads to the formation of a supramolecular polymer. We demonstrate that this effect is dependent on the concentration of the solution and on the polarity of the solvent. This effect can counteract the loss of viscosity of the solvent at elevated temperatures, thus opening an application of our systems as viscosity index improvers (VIIs) in working fluids. This was tested for different motor oils and led to the identification of one compound as a promising VII. © 2021 Ostwaldt et al.

Amino acids are key building blocks for the synthesis of chiral organic materials. In this context, α-azido amino acids are interesting starting materials which allow the construction of functionalized, amino-acid based compounds by copper-catalyzed alkyne-azide click reactions. We have now employed this strategy for the synthesis of arginine-derivatives and found that the formation of the azide and the click reaction can be carried out in good yields and with almost no loss of stereopurity. However, further transformation by saponification/amide-formation led to significant racemization at the α-carbon. This process was investigated in detail, showing that the triazole-moiety seems to be responsible for the facile racemization. Thus, the highly useful modification of α-azido amino acids by the CuAAC-reaction needs to be used with caution when stereopure materials are desired. ©AUTHOR(S)

The oxidative Weimberg pathway for the five-step pentose degradation to α-ketoglutarate is a key route for sustainable bioconversion of lignocellulosic biomass to added-value products and biofuels. The oxidative pathway from Caulobacter crescentus has been employed in in-vivo metabolic engineering with intact cells and in in-vitro enzyme cascades. The performance of such engineering approaches is often hampered by systems complexity, caused by non-linear kinetics and allosteric regulatory mechanisms. Here we report an iterative approach to construct and validate a quantitative model for the Weimberg pathway. Two sensitive points in pathway performance have been identified as follows: (1) product inhibition of the dehydrogenases (particularly in the absence of an efficient NAD+ recycling mechanism) and (2) balancing the activities of the dehydratases. The resulting model is utilized to design enzyme cascades for optimized conversion and to analyse pathway performance in C. cresensus cell-free extracts. © 2020, The Author(s).

A coumarin based probe for the efficient detection of hydrogen sulfide in aqueous medium is reported. The investigated coumarine-based derivative forms spherical nanoparticles in aqueous media. In presence of Pd2+, a metallosupramolecular coordination polymer is formed, which is accompanied by quenching of the coumarin emission at 390 nm. Its Pd2+ complex could be used as a probe for chemoselective detection of monohydrogensulfide (HS−). Presence of HS− leads to a'turn-on' fluorescence signal, resulting from decomplexation of Pd2+ from the metallosupramolecular probe. The probe was successfully applied for qualitative and quantitative detection of HS− in different sources of water directly collected from sea, river, tap and laboratory drain water, as well as in growth media for aquatic species. © 2020 The Authors. Published by Wiley-VCH Verlag GmbH & Co. KGaA.

Peptide amphiphiles with well-organized secondary structure are an important family of molecules that are known to assemble into a variety of nanostructures. In this work, we present three guanidiniocarbonylpyrrole (GCP) containing peptide amphiphiles, which show versatile morphology and secondary structure changes as a result of different chain lengths and in different concentration regimes. The random coil conformation, α-helix, and β-sheet are obtained for peptide 1, peptide 2, and peptide 3, respectively under neutral aqueous conditions. Furthermore, all peptide amphiphiles can aggregate to form nanoparticles at low concentrations. However, at high concentrations, peptide 1 self-assembles into left-handed twisted helical fibers, while longer bamboo-like morphology can be observed exclusively for peptide 2. For peptide 3, freshly prepared samples show uniform spherical morphology, whereas an obvious morphological transition from original nanoparticles to disordered fibers was realized after incubating for one week. These fascinating morphology changes were determined by the combination of circular dichroism, dynamic light scattering, transmission electron microscopy, atomic force microscopy, and theoretical calculations. © 2020 The Author

The dual pH-induced reversible self-assembly (PIRSA) of Au-nanoparticles (Au NPs) is reported, based on their decoration with the self-complementary guanidiniocarbonyl pyrrole carboxylate zwitterion (GCPZ). The assembly of such functionalized Au NPs is found at neutral pH, based on supramolecular pairing of the GCPZ groups. The resulting self-assembled system can be switched back to the disassembled state by addition of base or acid. Two predominant effects that contribute to the dual-PIRSA of Au NPs are identified, namely the ionic hydrogen bonding between the GCPZ groups, but also a strong hydrophobic effect. The contribution of each interaction is depending on the concentration of GCPZ on NPs, which allows to control the self-assembly state over a wide range of different water/solvent ratios. © 2020 The Authors. Published by WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim

Supramolecular organocatalysis has emerged as a novel research field in the context of homogeneous catalysis. In particular, the use of functionalized macrocycles as supramolecular catalysts is highly promising, as these systems are oftentimes easily accessible and offer distinct advantages in catalysis. Macrocyclic catalysts can provide defined binding pockets, such as hydrophobic cavities, and can thus create a reaction microenvironment for catalysis. In addition, macrocycles can offer a preorganized arrangement of functional groups, such as binding sites or catalytically active groups, thus enabling a defined and possibly multivalent binding and activation of substrates. The aim of this Minireview is to provide an overview of recent advances in the area of supramolecular organocatalysis based on functionalized macrocycles (including cyclodextrins, calixarenes, and resorcinarenes), with a focus on those examples where certain catalytically active groups (such as hydrogen bond donors/acceptors, Brønsted acid or base groups, or nucleophilic units) are present in or have been installed on the macrocycles. © 2020 The Authors. Published by Wiley-VCH Verlag GmbH & Co. KGaA.

In this Minireview, an overview about the past 20 years of the guanidiniocarbonyl-pyrrole (GCP) binding motif, which was designed, investigated and applied by Prof. Dr. Carsten Schmuck, is presented. Here we highlight the first steps from design and discovery, initial binding studies, applications in material science to advanced biomedical use in protein modulation and delivery of genetic material. © 2020 The Authors. Published by Wiley-VCH Verlag GmbH & Co. KGaA.

Heterobifunctional rotaxanes serve as efficient catalysts for the addition of malonates to Michael acceptors. We report a series of four different heterobifunctional rotaxanes, featuring an amine-based thread and a chiral 1,1′-binaphthyl-phosphoric-acid-based macrocycle. High-level DFT calculations provided mechanistic insights and enabled rational catalyst improvements, leading to interlocked catalysts that surpass their non-interlocked counterparts in terms of reaction rates and stereoselectivities. © 2019 The Authors. Published by Wiley-VCH Verlag GmbH & Co. KGaA.

Several modes of supramolecular assembly relying on noncovalent as well as dynamic covalent interactions were combined in a single molecule. The supramolecular self-assembly of 1 can be controlled by three stimuli, namely light, pH, and addition of metal ions, in both organic and aqueous media. The multi-stimuli-responsive nature of 1 was used successfully for the controlled encapsulation and on-demand release of hydrophobic molecules, such as dyes and drugs. © 2019 American Chemical Society.

Bis-BINOL derivatives have proven highly useful in applications such as chemosensing or organocatalysis. In this account, we describe strategies for the linking of BINOL units via the 3-, 4-, or 5-positions, showing that unique synthetic strategies are necessary to address each position. We report the synthesis of suitable C 1 -symmetric precursors, which are generated either by monohalogenation or by monodeprotection of C 2 -symmetric starting materials, and their subsequent coupling to give linked bis-BINOL derivatives. © 2020 American Institute of Physics Inc.. All rights reserved.

Organocatalysis has revolutionized asymmetric synthesis. However, the supramolecular interactions of organocatalysts in solution are often neglected, although the formation of catalyst aggregates can have a strong impact on the catalytic reaction. For phosphoric acid based organocatalysts, we have now established that catalyst-catalyst interactions can be suppressed by using macrocyclic catalysts, which react predominantly in a monomeric fashion, while they can be favored by integration into a bifunctional catenane, which reacts mainly as phosphoric acid dimers. For acyclic phosphoric acids, we found a strongly concentration dependent behavior, involving both monomeric and dimeric catalytic pathways. Based on a detailed experimental analysis, DFT-calculations and direct NMR-based observation of the catalyst aggregates, we could demonstrate that intermolecular acid-acid interactions have a drastic influence on the reaction rate and stereoselectivity of asymmetric transfer-hydrogenation catalyzed by chiral phosphoric acids. © The Royal Society of Chemistry 2020.

Two supramolecular nanocapsules were generated by multi-component self-assembly of the novel bisphosphoric acid (R,R)-6 with suitable bis- and trisamidines. The resulting chiral, hydrogen-bonded capsules are stable even in polar media and at low concentrations and can be employed for the binding of C70-fullerene in solution. © 2019 The Royal Society of Chemistry.

A series of covalently linked bis- and trisphosphoric acids was investigated for their application in the stereoselective transfer-hydrogenation of quinolines. In a combined experimental and theoretical study, it was found that the number and relative positioning of the chiral 1,1′-binaphthyl-phosphoric acid groups strongly influences the stereoselectivity of the reaction, based on two competing reaction mechanisms. While a single 3-monosubstituted phosphoric acid moiety gives rise to little enantioselectivity, correct positioning of two phosphoric acids allows a cooperative mechanism, resulting in significantly higher stereoselectivities. © 2019 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim

Interlocked molecules, such as rotaxanes, catenanes, and molecular knots, offer conceptually new possibilities for the generation of chiral chemosensors and catalysts. Due to the presence of the mechanical or topological bond, interlocked molecules can be used to design functional systems with unprecedented features, such as switchability and deep binding cavities. In addition, classical elements of chirality can be supplemented with mechanical or topological chirality, which have so far only scarcely been employed as sources of chirality for stereoselective applications. This minireview discusses recent examples in this emerging area, showing that the application of chiral interlocked molecules in sensing and catalysis offers many fascinating opportunities for future research. 1 Introduction 2 Interlocked Molecules with Chiral Subcomponents 2.1 Point Chirality 2.2 Axial Chirality 3 Mechanically Chiral Interlocked Molecules 4 Topologically Chiral Interlocked Molecules 5 Outlook. © Georg Thieme Verlag Stuttgart New York.

The synthesis and application of three chiral receptors based on the covalent linkage of 1,1′-binaphthylphosphoric acids is reported. The binding of the lysine enantiomers to the chiral receptors was investigated by DOSY-NMR and NMR titrations, revealing that the bisphosphoric acid 1d acts as a highly stereoselective receptor for binding of d-lysine. © 2018 American Chemical Society.

How can an assisting Brønsted-acid be beneficial in asymmetric Brønsted-acid catalysis? In this Minireview, we discuss selected examples of chiral organocatalysts that feature two acidic groups working cooperatively by virtue of intra- or intermolecular hydrogen-bonding. In these systems, the assisting Brønsted-acid can play different roles, ranging from simple hydrogen-bond donation, to substrate-binding or even as a nucleophilic reaction partner. By analysis of combined experimental, structural and theoretical data, we aim at developing a better understanding of the reaction mechanisms, which are largely influenced by the underlying intramolecular- and intermolecular catalyst-substrate interactions. This may aid in the future development of more selective dual Brønsted-acid organocatalysts for specific asymmetric transformations. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

The identification of structurally related analytes has become possible using sensor arrays, based on sets of cross-reactive chemosensors. This work reports the use of readily available chiral phosphoric acids for the array-based, chemo- and stereoselective sensing of l- and d-amino acids. Six bis- and trisphosphoric acids were used in combination with Ni2+ and Eu3+, resulting in a set of twelve chiral fluorescent chemosensors. This sensor-array enables a correct classification of l-amino acids with 100 % accuracy, while the differentiation between l- and d-amino acids can be achieved with 94 % accuracy. In addition, the systematic analysis of sensor contributions has allowed the use of a reduced set of seven sensors for the classification of l-amino acids, thus drastically reducing the amount of necessary measurements. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim

In this account, we describe the synthesis of a series of BINOL-based bis- and trisphosphoric acids 11d/e/f, which commonly feature an unusual phosphoric acid monoester motif. This motif is generated by an acid-catalyzed 5-endo-dig cyclization of the 3-alkynyl-substituted BINOL precursors to give the corresponding Furan-annelated derivatives, followed by phosphorylation of the remaining phenolic alcohols. In the cyclization reaction, we observed an unexpected partial racemization in the bis- and tris-BINOL scaffolds, leading to mixtures of diastereomers that were separated and characterized spectroscopically and by X-ray crystal structure analyses. The cyclization and racemization processes were investigated both experimentally and by DFT-calculations, showing that although the cyclization proceeds faster, the barrier for the acid-catalyzed binaphthyl-racemization is only slightly higher. © 2018 American Chemical Society.

Interlocked molecules, such as catenanes, rotaxanes, and molecular knots, have become interesting candidates for the development of sophisticated chemical catalysts. Herein, we report the first application of a catenane-based catalyst in asymmetric organocatalysis, revealing that the catenated catalyst shows dramatically increased stereoselectivities (up to 98 % ee) in comparison to its non-interlocked analogues. A mechanistic rationale for the observed differences was developed by DFT studies, suggesting that the involvement of two catalytically active groups in the stereodetermining reaction step is responsible for the superior selectivity of the interlocked catalyst. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim

We describe the straightforward synthesis of a series of bis-phosphoric acids (R,R)-1 a–d, featuring two chiral 1,1′-binaphthyl-phosphoric acid units that are tethered by rigid, π-conjugated linkers. The nature of the linker has a profound influence on the properties of the bis-phosphoric acids, such as their self-association behavior and their interaction with metal ions. This led to the identification of one preferred bis-phosphoric acid (R,R)-1 d, which shows selective fluorescence quenching in the presence of ferric ions (Fe3+). Thus, (R,R)-1 d could be applied for the detection of Fe3+, even in the presence of a variety of other metal ions. The chiral nature of the bis-phosphoric acid enables the interaction with Fe3+ to be followed by CD spectroscopy, providing a complementary detection mode with the same probe. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim

A novel [2]catenane was synthesised by ring-closing metathesis from a Ca-bisphosphate template. The resulting interlocked structure features two chiral 1,1′-binaphthyl-phosphates, leading to a bifunctional catenane structure. Initial binding studies point at the applicability of such mechanically interlocked bisphosphates as artificial receptors for dicationic guest molecules. © The Royal Society of Chemistry 2016.

The synthetic and reaction chemistries of cationic iminoborylene complexes [L<inf>n</inf>M=B=N=CR<inf>2</inf>]+, which feature a unique heterocumulene structure, have been systematically investigated. Precursors of the type CpFe(CO)<inf>2</inf>B(Cl)NCAr<inf>2</inf> (Ar = p-Tol/Mes, 5c/d) have been generated by B-centred substitution chemistry using CpFe(CO)<inf>2</inf>BCl<inf>2</inf> and suitable lithiated ketimines - a reaction which is found to be highly sensitive to the steric bulk at both the metal fragment and the ketimino group. Carbonyl/phosphine exchange (using PCy<inf>3</inf> or PPh<inf>3</inf>), followed by halide abstraction allows for the generation of the cationic iminoborylenes [CpFe(PR<inf>3</inf>)(CO)(BNCAr<inf>2</inf>)]+[BArX <inf>4</inf>]- (R = Cy, Ar = p-Tol/Mes, 12c/d; R = Ph, Ar = Mes, 13d; ArX = 3,5-X<inf>2</inf>C<inf>6</inf>H<inf>3</inf> where X = Cl, CF<inf>3</inf>) which have been characterized spectroscopically and by X-ray crystallography. The reactivity of these iminoborylene systems towards a range of nucleophiles and unsaturated substrates has been investigated. The latter includes the first examples of M=B metathesis reactivity with a carbodiimide, and results in Fe=B cleavage and formation of the isonitrile complexes [CpFe(PCy<inf>3</inf>)(CO)(CNR)]+[BArCl <inf>4</inf>]- (R = iPr/Cy, 16/17). © The Royal Society of Chemistry.

α versus γ: [CpFe(CO)(PCy3)(BNCMes 2)]+, synthesized by halide abstraction, represents the first example of a BN allenylidene analogue, and features an unsaturated MBNC π system. Although DFT calculations show significant LUMO amplitude at the γ (carbon) position, primary reactivity towards nucleophiles occurs at the sterically less hindered α (boron) center. © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Reaction of 2,6-dimesityl pyridine (Lpy) with BBr3 leads to the spontaneous formation of the trigonal dibromoborenium cation [Lpy·BBr2]+via bromide ejection. Systematic structural and computational studies, and the reactivity displayed by a closely related N-heterocyclic carbene (NHC) donor, reveal the role played by arene-borane interactions in this chemistry. [Lpy·BBr 2]+ features a structurally characterized (albeit weak) electrostatic interaction between the borane Lewis acid and flanking arene π systems. © 2011 The Royal Society of Chemistry.

Condensation of the O-protected planar chiral hydroxyferrocene carbaldehyde (Sp)-1 with ethylenedlarcime, followed by deprotection gave rise to the "ferro-salen" ligand (Sp,Sp)-3 in good yield. This scaffold was used for the preparation of a series of metal complexes [(Sp,Sp)-4/5/8], which were subsequently applied for the Lewis acid catalyzed asymmetric trimethylsilylcyanation of benzaldehyde. © 2010 Wiley-VCH Verlag GmbH & Co. KGaA.

Condensation of the O-protected hydroxyferrocene carbaldehyde (Sp)-1 with suitable diamines, followed by liberation of the hydroxyferrocene moiety leads to a new type of ferrocene-based salen ligands (3). While the use of ethylenediamine in the condensation reaction yields the planar-chiral ethylene-bridged ligand [(Sp,Sp)-3a], reaction with the enantiomers of trans-1,2-cyclohexylendiamine gives rise to the corresponding diastereomeric cyclohexylene-bridged systems [(S,S,Sp,Sp)-3b and (R,R,Sp,Sp)-3c], which feature a combination of a planar-chiral ferrocene unit with a centrochiral diamine backbone. Starting with the ferrocene-aldehyde derivative (Rp)-1, the enantiomeric ligand series (3d/e/f) is accessible via the same synthetic route. The (Sp)-series of these newly developed N2O2-type ligands was used for the construction of the corresponding mononuclear bis(isopropoxy)titanium (4a/b/c), methylaluminum (5a/b/c) and chloroaluminum-complexes (6a/b/c), which were isolated in good yields and identified by X-ray diffraction in several cases. The aluminum complexes (5/6) were successfully used in the Lewis-acid catalyzed addition of trimethylsilylcyanide to benzaldehyde, yielding the corresponding cyanohydrins in 45-62% enantiomeric excess. © 2010 Elsevier B.V. All rights reserved.