Chiral guanidine catalyzed cyclization reactions of 1,3-enynes for lactone synthesis: switchable H-bond catalysis

Zhang, Yongyan; Ning, Lichao; Zhu, Tianxin; Xie, Zheng; Dong, Shunxi; Feng, Xiaoming; Liu, Xiaohua

doi:10.1039/d4qo00374h

Cited by 7 publications

(3 citation statements)

References 40 publications

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“…One interesting approach to overcome some practical difficulties associated with superbases utilization is the in-situ generation of these catalysts [ 144 ]. The availability of chiral superbases is a notable addition to the arsenal of the superbase catalysis for enantioselective synthesis [ 145 ]. Another facet of modern organocatalysis is the development of polyfunctional catalysts.…”

Section: Overview and Prospectsmentioning

confidence: 99%

Strong Bases and beyond: The Prominent Contribution of Neutral Push–Pull Organic Molecules towards Superbases in the Gas Phase

Raczyńska,

Gal,

Maria

2024

IJMS

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In this review, the principles of gas-phase proton basicity measurements and theoretical calculations are recalled as a reminder of how the basicity PA/GB scale, based on Brønsted–Lowry theory, was constructed in the gas-phase (PA—proton affinity and/or GB—gas-phase basicity in the enthalpy and Gibbs energy scale, respectively). The origins of exceptionally strong gas-phase basicity of some organic nitrogen bases containing N-sp3 (amines), N-sp2 (imines, amidines, guanidines, polyguanides, phosphazenes), and N-sp (nitriles) are rationalized. In particular, the role of push–pull nitrogen bases in the development of the gas-phase basicity in the superbasicity region is emphasized. Some reasons for the difficulties in measurements for poly-functional nitrogen bases are highlighted. Various structural phenomena being in relation with gas-phase acid–base equilibria that should be considered in quantum-chemical calculations of PA/GB parameters are discussed. The preparation methods for strong organic push–pull bases containing a N-sp2 site of protonation are briefly reviewed. Finally, recent trends in research on neutral organic superbases, leaning toward catalytic and other remarkable applications, are underlined.

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Section: Overview and Prospectsmentioning

confidence: 99%

Strong Bases and beyond: The Prominent Contribution of Neutral Push–Pull Organic Molecules towards Superbases in the Gas Phase

Raczyńska,

Gal,

Maria

2024

IJMS

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“…In comparison, the corresponding hemisalt BG3 ·HCl led to the cis product with a low ee value. The chloride ion of guanidinium hydrochloride could be tightly bonded by hydrogens of the catalyst, which provided different hydrogen bond donors in comparison with the sterically hindered BAr F 4 anion. These results showed that hydrogen bond donors as well as their orientation could be adjusted by the amide linker and the counterions, which are critical to reactivity and stereoselectivity.…”

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confidence: 99%

“…In our endeavor to identify chiral guanidine-based organocatalysts and ligands, , we realized the annulation of p -quinols with azlactones to access dihydrobenzofuran-2,5-dione skeletons with a bisguanidinium catalyst . Though this process for p -quinols involved intermolecular conjugate addition/lactonization, we rationalized that the bifunctional catalysis and hydrogen bond activation mode could be applied to p -quinamines and ketenes (Scheme c), from which the two quaternary centers could be arranged.…”

mentioning

confidence: 99%

Asymmetric Synthesis of Hydroindoles via Desymmetrizing [3+2] Annulation of p-Quinamines and Arylalkylketenes

Chen,

Zhang,

Song

et al. 2024

Org. Lett.

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The asymmetric desymmetrizing [3+2] annulation reaction of p-quinamines and arylalkylketenes to synthesize hydroindoles was realized. Catalyzed by chiral bisguanidinium hemisalt via multiple hydrogen bond interactions, enantiomerically enriched products with reversal of diastereoselectivity in comparison with the racemic version were afforded in good yields under mild reaction conditions. Diaryl-substituted hydroindoles could also perform the Friedel−Crafts type of addition to give more complicated multicycles. Density functional theory calculations revealed that the enantio-and diastereoselectivity stem from varied hydrogen-bonding manners.

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Asymmetric Carbene Insertion into Se−S Bonds by Synergistic Rh(II)/Guanidine Catalysis Involving Chalcogen‐Bond Assistance

He,

Fu,

et al. 2024

Angewandte Chemie

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The efficient construction of chalcogen‐atom‐based chiral compounds remains a challenge, despite the importance of organoselenium and organosulfur compounds in life and materials science. Chalcogen atoms can form net attractive interactions called chalcogen bonds, but it is an undeveloped tool to assist asymmetric catalysis. Herein, we report an enantioselective insertion platform to install a stereogenic center bearing selanyl and thiocyano functional groups. Our method operates by synergistic catalysis by a chiral guanidine and an achiral dirhodium complex in a three‐component or four‐component reaction, through Se‐S bond insertion into carbene species, competing successfully with the spontaneous racemic process and showing high regioselectivity. As elucidated by spectroscopic experiments and computational studies, a unique mechanism involving chalcogen as well as hydrogen bonding was established to account for the enantiocontrol. The high stereoselectivity holds for a broad array of selanylthiocyanatopropanoates, which showed excellent anti‐inflammatory toward IL‐1β and low cytotoxicity.

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Chiral guanidine catalyzed cyclization reactions of 1,3-enynes for lactone synthesis: switchable H-bond catalysis

Abstract: H-bonding catalysis has attracted much attention in asymmetric reactions. Taking advantage of guanidine-amides as bifunctional organocatalysts, we successfully achieved cyclization as well as 1,4-conjugate addition/cyclization of azlactones with acyclic and...

Cited by 7 publications

References 40 publications

Strong Bases and beyond: The Prominent Contribution of Neutral Push–Pull Organic Molecules towards Superbases in the Gas Phase

Strong Bases and beyond: The Prominent Contribution of Neutral Push–Pull Organic Molecules towards Superbases in the Gas Phase

Asymmetric Synthesis of Hydroindoles via Desymmetrizing [3+2] Annulation of p-Quinamines and Arylalkylketenes

Asymmetric Carbene Insertion into Se−S Bonds by Synergistic Rh(II)/Guanidine Catalysis Involving Chalcogen‐Bond Assistance

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