The catalytic, enantioselective N-oxidation of substituted pyridines is described. The approach is predicated on a biomolecule-inspired catalytic cycle wherein high levels of asymmetric induction are provided by aspartic-acid-containing peptides as the aspartyl side chain shuttles between free acid and peracid forms. Desymmetrizations of bis(pyridine) substrates bearing a remote pro-stereogenic center substituted with a group capable of hydrogen bonding to the catalyst are demonstrated. Our approach presents a new entry into chiral pyridine frameworks in a heterocycle-rich molecular environment. Representative functionalizations of the enantioenriched pyridine N-oxides further document the utility of this approach. Demonstration of the asymmetric N-oxidation in two venerable drug-like scaffolds, Loratadine and Varenicline, show the likely generality of the method for highly variable and distinct chiral environments, while also revealing that the approach is applicable to both pyridines and 1,4-pyrazines.

The enantioselective synthesis of atropisomers is an emerging field, that in recent years reached fundamental results and put the bases for innovative applications. Organocatalysis is playing a central role in the realization of original synthesis for novel atropisomeric scaffolds. [1] In this short review, we would like to highlight the results obtained by our group and others in the field of axially enantioselective desymmetrization reactions using organocatalysis as main strategy.

The novel vinylogous aldol-lactonization cascade of alkylidene oxindole with trifluoromethyl ketones is presented. The reaction, catalyzed by a bifunctional tertiary amine, provides an efficient application of the vinylogous reactivity of alkylidene oxindoles for the preparation of enantioenriched trifluoromethylated α,β-unsaturated δ-lactones.

Contents  General S2 Screening of the reaction conditions S4 Determination of the absolute configuration S7 General procedure for the aEKC S14  Computational details S30 NMR traces S44  HPLC traces S69S2 General

A novel and straightforward synthesis of highly substituted isoquinoline-5,8-dione fused tricyclic pyrazoles is reported. The key step of the synthetic sequence is a regioselective, Ag CO promoted, 1,3-dipolar cycloaddition of C-heteroaryl-N-aryl nitrilimines and substituted isoquinoline-5,8-diones. The broad functional group tolerability and mild reaction conditions were found to be suitable for the preparation of a small library of compounds. These scaffolds were designed to interact with multiple biological residues, and two of them, after brief synthetic elaborations, were analyzed by molecular docking studies as potential anticancer drugs. In vitro studies confirmed the potent anticancer effects, showing promising IC values as low as 2.5 μm against three different glioblastoma cell lines. Their cytotoxic activity was finally positively correlated to their ability to inhibit PI3K/mTOR kinases, which are responsible for the regulation of diverse cellular processes in human cancer cells.

The catalytic, enantioselective N-oxidation of substituted pyridines is described. The approach is predicated on a biomolecule-inspired catalytic cycle wherein high levels of asymmetric induction are provided by aspartic acid containing peptides as the aspartyl side chain shuttles between free acid and peracid forms. Desymmetrizations of bis(pyridine) substrates bearing a remote pro stereogenic center are demonstrated, presenting a new entry into chiral pyridine frameworks in a heterocycle-rich molecular environment. Representative functionalizations of the enantioenriched pyridine N-oxides further document the utility of this approach. Demonstration of the asymmetric N-oxidation in two venerable drug-like scaffolds, Loratadine and Varenicline, show the likely generality of the method for highly variable and distinct chiral environments, while also revealing that the approach is applicable to both pyridines and 1,4-pyrazines. <br><br>

The vinylogous aldol addition of alkylidene oxindole with 1-trifluoromethyl-3-alkylidene-propan-2-ones was developed. The reaction, provides straightforward access to enantioenriched trifluoromethylated allylic alcohols.

A heterogeneous, silica‐based catalyst containing 9‐amino‐9‐deoxy‐epi‐quinine (or quinidine) and a derivative of benzoic acid was synthesized through radical thiol‐ene click reaction. The acid component allows the in situ activation of cinchona amino group, acting as a bifunctional catalyst. The heterogenized catalysts efficiently promoted the reaction of ketones with trans‐β‐nitrostyrene, with diastereo‐ and enantioselectivity comparable to those of the homogeneous counterparts (dr up to 90:10 and 90 % ee). In addition, the catalyst retained a constant activity for at least four cycles. Finally, the supported catalyst (9‐amino‐9‐deoxy‐epi‐quinine/achiral acid) was employed under continuous‐flow conditions. Two enantioselective Michael reactions were in sequence performed with the same homemade packed‐bed reactor. The addition of cyclohexanone to trans‐β‐nitrostyrene provided the evaluation of optimal residence time with high level of stereoselection (2 µL/min flow rate, 83 % ee). Furthermore, the flow reactor well performed in the preparation of warfarin (isolated yield 95 %, 78 % ee. in 16 h at room temperature). The dual (chiral amine/achiral acid) solid supported system, making an even easier work‐out, represents a valuable tool for green chemistry and is attractive for large scale applications.