Tandem [3 + 2] Cycloaddition/1,4-Addition Reaction of Azomethine Ylides and Aza-<i>o</i>-quinone Methides for Asymmetric Synthesis of Imidazolidines

Jia, Hao; Liu, Honglei; Guo, Zhenyan; Huang, Jiaxing; Guo, Hongchao

doi:10.1021/acs.orglett.7b02512

Cited by 44 publications

(7 citation statements)

References 72 publications

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“…[32] Furthermore, Guo and coworkers reported a silver(I)catalyzed synthesis of imidazolidines 58 from aza-o-QM precursors 56 and azomethine ylides 57 (2 equivalents) as shown in Scheme 11. [33] In this method, an equivalent of silveractivated azomethine ylide 57 undergoes [3 + 2] cycloaddition with the other equivalent of 57 to form imidazolidine intermediates. The subsequent capture of the in situ formed aza-o-QMs by the imidazolidines via 1,4-addition produces the desired products 58.…”

Section: Transition-metal Catalysismentioning

confidence: 99%

Aza‐Ortho‐Quinone Methides as Reactive Intermediates: Generation and Utility in Contemporary Asymmetric Synthesis

Liao

Miñoza

Lee

et al. 2022

Chemistry A European J

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The aza‐ortho‐quinone methide (aza‐o‐QM) chemistry has overwhelmingly progressed in the past few decades. This review aims to integrate various transition metal‐catalyzed and organocatalytic strategies in taming aza‐o‐QM intermediates, including the aza‐ortho‐vinylidene quinone methide (aza‐o‐VQM), aza‐ortho‐alkynyl quinone methide (aza‐o‐AQM), aza‐para‐quinone methide (aza‐p‐QM), and indole‐based aza‐o‐QM analog. These transient species are often utilized for the direct and enantioselective synthesis of complex (hetero)polycyclic or fused‐ring molecular scaffolds such as tetrahydroquinoline and indoline, among others, which are abundant in many natural products, bioactive compounds, and pharmaceuticals.

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Section: Transition-metal Catalysismentioning

confidence: 99%

Aza‐Ortho‐Quinone Methides as Reactive Intermediates: Generation and Utility in Contemporary Asymmetric Synthesis

Liao

Miñoza

Lee

et al. 2022

Chemistry A European J

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“…Although these motifs are lucrative both industrially and pharmaceutically, their synthesis advancement is very limited. A commonly implemented direct method for the synthesis of imidazolidine motif includes the 1,3-dipolar cycloaddition reaction , and condensation of 1,2-diamines with aldehydes, ketones, or oxo-compounds (Scheme a) . However, these processes are associated with the prefunctionalization of substrate and the use of expensive ligands .…”

Section: Introductionmentioning

confidence: 99%

Stereospecific Single-Pot Route to Chiral Imidazolidines from Aziridines Using a 2D Cu Metal–Organic Framework

et al. 2023

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The role of coordinatively unsaturated sites (CUS) in metal−organic framework (MOF)-catalyzed organic transformation is vital; however, the design and generation of such sites are challenging. We, therefore, report the synthesis of a novel two-dimensional (2D) MOF, [Cu(BTC)(Mim)] n (Cu-SKU-3), with pre-existing unsaturated Lewis acid sites. The presence of these active CUS facilitates a ready-to-use attribute in Cu-SKU-3, thereby subsiding the lengthy activation processes associated with MOF-based catalysis. The material has been completely characterized using single crystal X-ray diffraction (SCXRD), powder XRD (PXRD), thermogravimetric analysis (TGA), carbon, hydrogen, and nitrogen (CHN), Fourier-transform infrared (FTIR), and Brunauer−Emmett−Teller (BET) surface area analyses. We directly utilize Cu-SKU-3 for the synthesis of biologically valued chiral imidazolidine motifs in a one-pot fashion starting from aziridines. The chiral imidazolidines are synthesized in good yield (up to 89%) and with high optical purity (ee > 98−99%). Mechanistically, the transformation proceeds in a tandem fashion through stereospecific ring-opening of aziridines followed by the intramolecular cyclization (via sp 3 C−H functionalization) reaction forming chiral imidazolidines. The material has an excellent heterogeneous attribute and can be reused several times for one-pot catalytic cycles.

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“…As we know, a [4 + 2] cycloaddition reaction is among the most efficient approaches to access six-membered N -heterocycles via multiple bond formations in one pot, which usually features atom-economic reactions and improves the synthetic efficiency. , Recently, ortho -quinone methides ( o -QMs) and aza- ortho -quinone methides (ao-QMs) have attracted great attention in organic synthesis . As very reactive intermediates, they serve as general electrophiles to react with the nucleophiles to afford either [4 + n ] cycloaddition or 1,4-addition products through concerted or stepwise pathways . The [4 + 2] cycloadditions of o -QMs and ao-QMs with alkyl enolates and enamines have been explored extensively as a powerful and effective strategy to prepare benzopyran and tetrahdyroquinoline cores in organic synthesis (Scheme A). , For example, in 1999, Corey and co-workers first employed ao-QMs as useful synthons to form a series of hydroquinoline derivatives through intermolecular aza-Diels–Alder reactions, in which they found that the cycloaddition of ao-QMs with 2,3-dihydrofuran afforded tetrahydrofuro[2,3- b ]quinoline scaffolds (Scheme B) .…”

Section: Introductionmentioning

confidence: 99%

Synthesis of Furo[3,2-b]quinolines and Furo[2,3-b:4,5-b′]diquinolines through [4 + 2] Cycloaddition of Aza-o-Quinone Methides and Furans

et al. 2020

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An approach for the construction of furo[3,2-b]quinolines and furo[2,3-b:4,5-b′]diquinolines is developed through a metal-free [4 + 2] cycloaddition of easily available in situ generated aza-o-quinone methides and furans. The reaction tolerates a wide range of aza-o-quinone methides and substituted furans to afford the corresponding dihydro- or tetrahydrofuroquinolines in good to excellent yields. Mechanistic studies reveal that the reaction involves a concerted [4 + 2] cycloaddition pathway and shows a high regioselectivity of cycloaddition for a furan ring. The present method features mild reaction conditions, dearomatization of furans, high regio- and diastereoselectivity, gram-scalable preparations, and diversity of furoquinolines.

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Tandem [3 + 2] Cycloaddition/1,4-Addition Reaction of Azomethine Ylides and Aza-o-quinone Methides for Asymmetric Synthesis of Imidazolidines

Cited by 44 publications

References 72 publications

Aza‐Ortho‐Quinone Methides as Reactive Intermediates: Generation and Utility in Contemporary Asymmetric Synthesis

Aza‐Ortho‐Quinone Methides as Reactive Intermediates: Generation and Utility in Contemporary Asymmetric Synthesis

Stereospecific Single-Pot Route to Chiral Imidazolidines from Aziridines Using a 2D Cu Metal–Organic Framework

Synthesis of Furo[3,2-b]quinolines and Furo[2,3-b:4,5-b′]diquinolines through [4 + 2] Cycloaddition of Aza-o-Quinone Methides and Furans

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