General Asymmetric Synthesis of Densely Functionalized Pyrrolidines via Endo-Selective [3+2] Cycloaddition of β-Quaternary-Substituted Nitroalkenes and Azomethine Ylides

Enhancing the Efficacy of Chiral Ligands and Catalysts: Siloxane-Substituted Oxazoline Ferrocenes as Next-Generation Candidates

Since the discovery of classical chiral oxazoline ferrocene ligands in 1995, they have become pivotal in transition metal-catalyzed asymmetric transformations. Over the past decade, a notable evolution has been observed with the emergence of siloxane-substituted oxazoline ferrocenes, demonstrating significant potential as chiral ligands and catalysts. These compounds have consistently delivered exceptional results in diverse and mechanistically distinct transformations, surpassing the capabilities of classical oxazoline ferrocene ligands. This review meticulously delineates the research progress on siloxane-substituted oxazoline ferrocene compounds. It encompasses the synthesis of crucial precursors and desired products, highlights their achievements in asymmetric catalysis reactions, and delves into the exploration of the derivatization of these compounds, emphasizing the introduction of ionophilic groups and their impact on the recovery of transition metal catalysts. In addition to presenting the current state of knowledge, this review propels future research directions by identifying potential topics for further investigation concerning the siloxane-tagged derivatives. These derivatives are poised to be promising candidates for the next generation of highly efficient ligands and catalysts.

Well-defined Cu(I) complexes based on [N,P]-pyrrole ligands catalyzed a highly endoselective 1,3-dipolar cycloaddition

We herein report the synthesis and catalytic application of a new family of dinuclear Cu(I) complexes based on [N,P]-pyrrole ligands. The Cu(I) complexes (4a-d) were obtained in good yields and their catalytic properties were evaluated in the1,3-dipolar cycloaddition of azomethine ylides and electron-deficient alkenes. The air-stable complexes 4a-d exhibited high endo-diasteroselectivity to obtain substituted pyrrolidines, and the catalytic system showed excellent reactivity and wide substitution tolerance.

Enabling Asymmetric Synthesis of ABBV-3748, a Corrector Compound for the Treatment of Cystic Fibrosis

ABBV-3748 is a C2 corrector for the treatment of cystic fibrosis profiled among AbbVie's CFTR portfolio. A decagram-scale enabling asymmetric synthesis is described which addresses numerous shortcomings of the original route. Highlights include an InBr₃-catalyzed intramolecular hydroarylation reaction that rapidly assembles the chromane core, an exceptionally efficient asymmetric hydrogenation of a primary enamide, and identification of tBuMgCl as a uniquely effective base in a challenging acyl sulfonamide formation.

The Synthesis of Five-Membered N-Heterocycles by Cycloaddition of Nitroalkenes with (In)Organic Azides and Other 1,3-Dipoles

Cycloaddition reactions have emerged as rapid and powerful methods for constructing heterocycles and carbocycles. [3+2] Cyclo­additions of nitroalkenes with various 1,3-dipoles have been an interesting research area for many organic chemists. This review outlines the synthesis of N-substituted and NH-1,2,3-triazoles along with other five-membered N-heterocycles through cycloaddition reactions of nitro­alkenes.

1 Introduction

2 Synthesis of 1,2,3-Triazoles

2.1 Synthesis of NH-1,2,3-Triazoles

2.2 Synthesis of N-Substituted 1,2,3-Triazoles

3 Synthesis of Pyrrolidines and Pyrroles

4 Synthesis of Pyrazoles

5 Conclusion

Catalytic Asymmetric Dearomative 1,3-Dipolar Cycloaddition of 2-Nitrobenzothiophenes and Isatin-Derived Azomethine Ylides

An enantioselective dearomative 1,3-dipolar cycloaddition of 2-nitrobenzothiophenes and isatin-derived azomethine ylides with a bifunctional hydrogen-bonding thiourea catalyst was established, giving polyheterocyclic compounds in excellent results (up to 99% yield, >20:1 dr for all cases and up to 99% ee). The enantioselectivity could be reversed by the bifunctional hydrogen-bonding squaramide catalyst containing the same chiral source as in the thiourea catalyst. DFT calculations revealed the origin of the observed stereochemistry and the reversal of enantioselectivity.

Fueling the Pipeline via Innovations in Organic Synthesis

The paramount importance of synthetic organic chemistry in the pharmaceutical industry arises from the necessity to physically prepare all designed molecules to obtain key data to feed the design-synthesis-data cycle, with the medicinal chemist at the center of this cycle. Synthesis specialists accelerate the cycle of medicinal chemistry innovation by rapidly identifying and executing impactful synthetic methods and strategies to accomplish project goals, addressing the synthetic accessibility bottleneck that often plagues discovery efforts. At AbbVie, Discovery Synthesis Groups (DSGs) such as Centralized Organic Synthesis (COS) have been deployed as embedded members of medicinal chemistry teams, filling the gap between discovery and process chemistry. COS chemists provide synthetic tools, scaffolds, and lead compounds to fuel the pipeline. Examples of project contributions from neuroscience, cystic fibrosis, and virology illustrate the impact of the DSG approach. In the first ten years of innovative science in pursuit of excellence in synthesis, several advanced drug candidates, including ABBV-2222 (galicaftor) for cystic fibrosis and foslevodopa/foscarbidopa for Parkinson's disease, have emerged with key contributions from COS.

Multi-Ion Bridged Pathway of N-Oxides to 1,3-Dipole Dilithium Oxide Complexes

Roussi's landmark work on the generation of 1,3-dipoles from tertiary amine N-oxides has not reached its full potential since its underlying mechanism is neither well explored nor understood. Two competing mechanisms were previously proposed to explain the transformation involving either an iminium ion or a diradical intermediate. Our investigation has revealed an alternative mechanistic pathway that explains experimental results and provides significant insights to guide the creation of new N-oxide reagents beyond tertiary alkylamines for direct synthetic transformations. Truhlar's M06-2x functional and Møller-Plesset second-order perturbation theory with Dunning's [jul,aug]-cc-pv[D,T]z basis sets and discrete-continuum solvation models were employed to determine activation enthalpies and structures. During these mechanistic explorations, we discovered a unique multi-ion bridged pathway resulting from the rate-determining step, which was energetically more favorable than other alternate mechanisms. This newly proposed mechanism contains no electrophilic intermediates, strengthening the reaction potential by broadening the reagent scope and limiting the possible side reactions. This thoroughly defined general mechanism supports a more direct route for improving the use of N-oxides in generating azomethine ylide-dilithium oxide complexes with expanded functional group tolerance and breadth of chemistry.