Enantiopure imidazolinium-dithiocarboxylates as highly selective novel organocatalysts

Sereda, Oksana; Blanrue, Amélie; Wilhelm, René

doi:10.1039/b817991c

Cited by 44 publications

(23 citation statements)

References 35 publications

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“…[23] Chiral enantiopure versions of these organocatalysts were subsequently applied to the asymmetric synthesis of β-lactams by the Staudinger reaction. [24] In view of the rich chemistry exhibited by NHC·CO 2 and NHC·CS 2 betaines, and the marked differences between these two types of compounds, we launched a program to investigate the structural properties and reactivity of the related NHC·COS zwitterions. To the best of our knowledge, such adducts have never been described in the literature.…”

Section: Introductionmentioning

confidence: 99%

Synthesis and Organocatalytic Applications of Imidazol(in)ium‐2‐thiocarboxylates

2011

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Five imidazol(in)ium-2-thiocarboxylates bearing cyclohexyl, mesityl, or 2,6-diisopropylphenyl substituents on their nitrogen atoms were prepared from the corresponding imidazol(in)ium chlorides or tetrafluoroborates in a one-pot, twostep procedure involving the in situ generation of free Nheterocyclic carbenes (NHCs) with a strong base followed by trapping with carbonyl sulfide. The resulting NHC·COS zwitterions were isolated in high yields and characterized by IR and NMR spectroscopy. The molecular structure of SIMes·COS was determined by X-ray diffraction analysis. Experimental data and DFT calculations indicated that the negative charge on the thiocarboxylate anion is preferentially delocalized on the sulfur atom. Thermogravimetric

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Section: Introductionmentioning

confidence: 99%

Synthesis and Organocatalytic Applications of Imidazol(in)ium‐2‐thiocarboxylates

2011

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“…An enantioselective Staudinger reaction of ketene 174 and imine 173 with imidazolinium-dithiocarboxylate catalyst (175) was developed by Wilhelm, et al, Scheme 3.55 [71].…”

Section: [2 + 2] Cycloadditionsmentioning

confidence: 99%

Organocatalyzed Cycloadditions

Hong¹

2011

Enantioselective Organocatalyzed Reactions II

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Cycloadditions have been for a long time one of the most useful reactions in organic synthesis. Recently, the ability to promote the reactions by organocatalysts further expands the realm of its synthetic application. This review aims to highlight the recent advances in this area with particular emphasis on the asymmetric cycloaddition promoted by organocatalysts. IntroductionGenerating selectively the maximum number of bonds and stereogenic centers in a one-step (or one-pot) reaction constitute to be of key interest in synthetic chemistry. Among many methodologies for the objective, cycloaddition stand out. While searching for a better and tunable catalyst able to promote a wide spectrum of cycloaddition, organocatalysis was revealed as a powerful tool for efficient operations and many other merits, e.g., high stereoselectivity, moisture and air resistant, environmental benign and user friendly. Surprisingly, organocatalytic synthesis was virtually dominant for few decades until just the turn of this century [1]; nevertheless, it soon become the focal point, and it has occupied an important chapter in the modern synthetic chemistry [2]. In a very short period of time, more than hundred review articles of organocatalytic reactions were reported, and the papers are continuing to appear for summarizing up the thriving and robust subject. Several theoretical studies, including the computational Intramolecular CycloadditionsIn 2005, MacMillan reported an enantioselective organocatalytic intramolecular Diels-Alder reaction (IMDA) of a,b-unsaturated aldehyde and diene, as well as the application in the asymmetric synthesis of solanapyrone D (6), Scheme 3.1 [5]. Later, Danishefsky and Christmann individually reported the total synthesis of UCS1025A (9) by coupling reaction with MacMillan aldehyde (8) [6]. The malimide analogue 10 of the telomerase inhibitor UCS1025A (9) was also prepared by Christmann et al. by modified MacMillan's conditions (10 mol% catalyst loading in nitromethane, affording 74% yield and >99% ee after a sequence of recrystallization and oxidation), Scheme 3.2 [7]. In 2003, an interesting intramolecular organocatalytic [3 + 2] dipolar cycloaddition of an enynoate (19) catalyzed by PBu 3 was developed by Krische and his coworker in the total synthesis of (±)-hirsutene (21), Scheme 3.6 [12]. The intramolecular phosphane-catalyzed [3 + 2] dipolar cycloaddition provides a concise approach to the linear triquinane hirsutene, whereby three contiguous stereogenic centers are created and controlled in a single reaction step.A light-driven enantioselective organocatalysis intramolecular [2 + 2] photocycloaddition of quinolone (24) [4 + 2] cycloadditions. The enantioselectivity was rationalized by the fact that selective formation of the (E)-iminium isomer to avoid nonbonding interactions between the substrate olefin and the geminal methyl substituents and the benzyl group on the catalyst framework which effectively shields the re face of the dienophile, leaving the si face exposed to cycloadditio...

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“…6 The more Lewis basic nature of imidazolium dithiocarboxylates has allowed them to be used successfully as catalysts for the cyanosilylation of aldehydes, 7 and in the Staudinger reaction to prepare β-lactams. 8 Delaude demonstrated that the NHC·CS 2 can also be used as ligand and coordinates as a κ 2 ,S,S′ chelate to the Ru II centre in the first examples of transition-metal complexes with such ligands (B in Chart 1). His experiments also demonstrated the greater stability of the NHC·CS 2 than NHC·CO 2 betaines towards CE 2 loss.…”

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confidence: 99%

Self-Assembly Fabrication of Hollow Mesoporous Silica@Co–Al Layered Double Hydroxide@Graphene and Application in Toxic Effluents Elimination

Jiang

Song

Zeng

et al. 2015

ACS Appl. Mater. Interfaces

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Here, we propose a self-assembly process to prepare hierarchical HM-SiO2@Co–Al LDH@graphene, with the purpose of combining their outstanding performance. Hollow mesoporous silica was first synthesized as the core, using a novel sonochemical method, followed by a controlled shell coating process and chemical reduction. As a result of the electrostatic potential difference among HM-SiO2, Co–Al LDH, and graphene oxide, the HM-SiO2 spheres were coated by Co–Al LDH and graphene. Subsequently, the HM-SiO2@Co–Al LDH@graphene spheres were introduced into an epoxy resin (EP) matrix for investigation of their toxic effluents capture and elimination effectiveness during combustion. The amount of toxic CO and volatile organic compounds from the epoxy resin decomposition significantly suppressed after incorporating the HM-SiO2@Co–Al LDH@graphene hybrids, implying a reduced toxicity.

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Enantiopure imidazolinium-dithiocarboxylates as highly selective novel organocatalysts

Abstract: Asymmetric imidazolinium-dithiocarboxylates have been found for the first time to be highly selective catalysts; in the present case, the novel organocatalysts were able to catalyze the Staudinger reaction in up to 96% ee and 99% yield.

Cited by 44 publications

References 35 publications

Synthesis and Organocatalytic Applications of Imidazol(in)ium‐2‐thiocarboxylates

Synthesis and Organocatalytic Applications of Imidazol(in)ium‐2‐thiocarboxylates

Organocatalyzed Cycloadditions

Self-Assembly Fabrication of Hollow Mesoporous Silica@Co–Al Layered Double Hydroxide@Graphene and Application in Toxic Effluents Elimination

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