Elemental‐Sulfur‐Promoted C(sp<sup>3</sup>)−H Activation of Methyl Heteroarenes Leading to Thioamides

Liu, Jianming; Zhao, Shanshan; Yan, Xuyang; Zhang, Yanyan; Zhao, Shufang; Zhuo, Kelei; Yue, Yuanyuan

doi:10.1002/ajoc.201700532

Cited by 16 publications

(10 citation statements)

References 73 publications

(14 reference statements)

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“…Next, the screening of polar aprotic solvents such as EtOAc, THF and 1,4-dioxane revealed that THF solvent was superior than the other two solvents as it gave 68% yield of the product. The use of chlorinated solvents such as DCE and TCE and non-polar solvent such as toluene did not increase the product yield (entries [8][9][10]. When PEG 200 was used as the solvent, it rendered the product in 77% yield (entry 11).…”

Section: Resultsmentioning

confidence: 99%

“…[3] However, shortcomings, such as the use of pyrophoric base and the need of cryogenic temperature, associated with this approach were first overcome by Huang and co-workers by treating 2-methylazaarenes with N-sulfonyl aldimines using Pd(OAc) 2 /1,10-phen catalyst (Scheme 1b). [4] Afterwards, both Brønsted acid [5] and Lewis acid [6][7] catalyzed transformations, as well as transition metalfree [8] and asymmetric [9] approaches have been reported by varying the electrophiles (Scheme 1c). Although these transformations have many benefits, they require the use of corrosive Brønsted acid and homogeneous Lewis acid catalysts and external ligand, and most of the reports were not focused on the recovery of the catalysts.…”

Section: Introductionmentioning

confidence: 99%

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Ligand‐Free and Reusable Palladium Nanoparticles‐Catalyzed Alkylation of 2‐Alkylazaarenes with Activated Ketones under Neutral Conditions

2019

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A mild, efficient, and stable binaphthyl-stabilized palladium nanoparticles (PdÀ BNP) catalyzed (sp 3 )CÀ H reaction of 2-alkylazaarenes with activated carbonyl compounds was developed. Various activated carbonyl compounds such as α-keto amide, isatin, 1,2-diketone, α-keto ester, trifluoromethyl ketone, and phenylglyoxal derivatives were examined and most of the compounds underwent the reaction smoothly to provide the corresponding products in moderate to excellent yields. Moreover, chemoselective reactions of αketo amides in the presence of simple ketones were achieved. Also, the model reaction was extended to a gram-scale synthesis and some of the products were utilized for derivatization to form the corresponding Noxides, acryl amides and 1,2-diol, respectively. The major advantages of the protocol are neutral reaction conditions, no additional requirement of external ligand, and successful reusability of the PdÀ BNP catalyst up to five cycles without losing its activity and yield. Hg-poisoning and hot filtration tests confirmed the heterogeneity of the PdÀ BNP catalyst.[a] Reaction conditions: 1 (1.5 mmol) and 2 (0.5 mmol) were used in 2 mL of PEG 200. [b] Isolated yield.[a] Reaction conditions: 1 (1.5 mmol) and 4 (0.5 mmol) were used in 2 mL of PEG 200. [b] Isolated yield. Scheme 2. Reaction of quinaldine with activated ketones. Scheme 3. Gram-scale synthesis. 56% yield (104.7 mg); Colourless solid; mp 156-157°C (Lit. [10] mp 155-157°C); R f = 0.53 (30% ethyl acetate in hexanes); 1 H NMR (400 MHz, CDCl 3 ): δ = 2.46 (s, 3H), 2.63 (s, 3H), 3.43 (d, J = 14.8 Hz, 1H), 3.77 (d, J = 15.2 Hz, 1H), 6.93 (d, J = 7.6 Hz, 1H), 6.97-7.10 (m, 2H), 7.22 (t, J = 6.8 Hz, 1H), 7.32 (t, J = 7.2 Hz, 2H), 7.39-7.51 (m, 2H), 7.84 (t, J = 8.8 Hz,

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Ligand‐Free and Reusable Palladium Nanoparticles‐Catalyzed Alkylation of 2‐Alkylazaarenes with Activated Ketones under Neutral Conditions

2019

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“…Intermediate V undergoes dehydration and easily converted to intermediate VI . Meanwhile, elemental sulfur undergoes nucleophilic attack by morpholine, to afford polysulfide IV . Then, intermediate IV reacts with intermediate VI to afford intermediate VII .…”

Section: Resultsmentioning

confidence: 99%

“…Then, intermediate IV reacts with intermediate VI to afford intermediate VII . Owing to the presence of the extra hydrogen on the methylene group of the imine, intermediate VII oxidizes to release the final product 4 A in the presence of an amino sulfur species …”

Section: Resultsmentioning

confidence: 99%

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Simple and Highly Efficient Synthesis of Thioamide Derivatives Using β‐Cyclodextrin as Supramolecular Catalyst in Water

2018

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A simple, straightforward and highly efficient approach for the synthesis of thioamide derivatives in water at 100 oC has been developed. Total 22 compounds were prepared via a one‐pot multicomponent reaction between substituted aldehydes, sulfur powder and secondary amines by using recyclable catalyst β‐cyclodextrin indicating the broad substrate scope of this method. The salient features of the present protocol are water as a green solvent, non‐toxic catalyst, good to excellent yields of products, operational simplicity, eco‐friendliness and easy isolation of products. The used catalyst was recovered and reused several times without significant loss of catalytic activity, which is an essential parameter of green synthesis.

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Synthesis of Phosphoryl Thioamides via Three‐Component Reaction of Phosphinic Chlorides with Amines and Sulfur

et al. 2019

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A straightforward, practical, and atom‐economical three‐component synthesis of phosphoryl thioamides from phosphinic chlorides, elemental sulfur, and aliphatic amines has been developed. The scope and limitations of this transformation have been investigated. This protocol is distinguished by metal‐ and organic solvent‐free conditions, and high tolerance to various functional groups; it can be adapted for scaled‐up synthesis.magnified image

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Elemental‐Sulfur‐Promoted C(sp³)−H Activation of Methyl Heteroarenes Leading to Thioamides

Cited by 16 publications

References 73 publications

Ligand‐Free and Reusable Palladium Nanoparticles‐Catalyzed Alkylation of 2‐Alkylazaarenes with Activated Ketones under Neutral Conditions

Ligand‐Free and Reusable Palladium Nanoparticles‐Catalyzed Alkylation of 2‐Alkylazaarenes with Activated Ketones under Neutral Conditions

Simple and Highly Efficient Synthesis of Thioamide Derivatives Using β‐Cyclodextrin as Supramolecular Catalyst in Water

Synthesis of Phosphoryl Thioamides via Three‐Component Reaction of Phosphinic Chlorides with Amines and Sulfur

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Elemental‐Sulfur‐Promoted C(sp3)−H Activation of Methyl Heteroarenes Leading to Thioamides

Cited by 16 publications

References 73 publications

Ligand‐Free and Reusable Palladium Nanoparticles‐Catalyzed Alkylation of 2‐Alkylazaarenes with Activated Ketones under Neutral Conditions

Ligand‐Free and Reusable Palladium Nanoparticles‐Catalyzed Alkylation of 2‐Alkylazaarenes with Activated Ketones under Neutral Conditions

Simple and Highly Efficient Synthesis of Thioamide Derivatives Using β‐Cyclodextrin as Supramolecular Catalyst in Water

Synthesis of Phosphoryl Thioamides via Three‐Component Reaction of Phosphinic Chlorides with Amines and Sulfur

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Elemental‐Sulfur‐Promoted C(sp³)−H Activation of Methyl Heteroarenes Leading to Thioamides