- Chlorotrimethylsilane - A novel catalyst in friedel-crafts reaction
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In the Friedel-Crafts condensation of diaryl carbinol with substituted phenols, the use of chlorotrimethylsilane (CTMS) as catalyst, leads to the formation of triarylmethanes under mild conditions. 6-Methoxy- 1,2,3,4- tetrahydronaphthalen- 1-ol under similar condition, on condensation with o- cresol, gives 1-(4-hydroxy-3-methyl phenyl)-6-methoxy-1,2,3,4- tetrahydronaphthalene.
- Srivastava, Neeta,Kumar, Atul,Dwivedy, Indra,Ray, Suprabhat
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- Catalytic Asymmetric Three-component Hydroacyloxylation/ 1,4-Conjugate Addition of Ynamides
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A highly enantioselective three-component hydroacyloxylation/1,4-conjugate addition of ortho-hydroxybenzyl alcohols, ynamides and carboxylic acids was developed under mild reaction conditions in the presence of a chiral N,N′-dioxide/Sc(OTf)3 complex, which went through in situ generated ortho-quinone methides with α-acyloxyenamides, delivering a range of corresponding chiral α-acyloxyenamides derivatives containing gem(1,1)-diaryl skeletons in moderate to good yields with excellent ee values. The scale-up experiment and further derivation showed the practicality of this catalytic system. In addition, a possible catalytic cycle and transition state model was proposed to elucidate the origin of the stereoselectivity based on X-ray crystal structure of the α-acyloxyenamide intermediate and product.
- Cao, Weidi,Feng, Xiaoming,Jiang, Mingyi,Li, Xiangqiang,Zhan, Tangyu
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supporting information
(2020/06/17)
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- A Simple Synthesis of Densely Substituted Benzofurans by Domino Reaction of 2-Hydroxybenzyl Alcohols with 2-Substituted Furans
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The Br?nsted acid-catalyzed cascade synthesis of densely substituted benzofurans from easily available salicyl alcohols and biomass-derived furans has been developed. The disclosed sequence includes the intermediate formation of 2-(2-hydroxybenzyl)furans
- Abaev, Vladimir T.,Chalikidi, Petrakis N.,Kekhvaeva, Anna E.,Makarov, Anton S.,Trushkov, Igor V.,Uchuskin, Maxim G.
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p. 3747 - 3757
(2019/09/30)
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- [4 + 2]-Cycloaddition and 1,4-Addition of ortho-Quinone Methides by a Chiral Crotyl Silane
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Anhydrous FeCl3 in the presence of 2,6-lutidine promotes the substrate-controlled enantioselective [4 + 2]-cycloaddition and crotylation reaction between an enantioenriched (S,E)-crotyl silane and in situ generated ortho-quinone methides (oQMs)
- Wong, Christopher R.,Hummel, Gerald,Cai, Yongqi,Schaus, Scott E.,Panek, James S.
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supporting information
p. 32 - 35
(2019/01/04)
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- A base-promoted cascade reaction of α,β-unsaturated: N -tosylhydrazones with o -hydroxybenzyl alcohols: Highly regioselective synthesis of N-sec -alkylpyrazoles
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An efficient method for the synthesis of N-sec-alkylpyrazoles through a base-promoted cascade cyclization/Michael addition reaction of α,β-unsaturated N-tosylhydrazones with ortho-hydroxybenzyl alcohols has been developed. The desired products containing di- or triaryl groups at the same carbon atom were afforded in good to excellent yields with excellent regioselectivities (>20:1). Moreover, a three-component reaction of ortho-hydroxybenzyl alcohols, α,β-unsaturated N-tosylhydrazones and saturated N-tosylhydrazones also took place to afford pyrazoles in good yields. This reaction offers a new route to triarylmethanes with a simple operation and is applicable for large-scale synthesis.
- Chen, Lian-Mei,Zhao, Juan,Xia, An-Jie,Guo, Xiao-Qiang,Gan, Ya,Zhou, Chuang,Yang, Zai-Jun,Yang, Jun,Kang, Tai-Ran
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supporting information
p. 8561 - 8570
(2019/10/02)
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- Organocatalytic Asymmetric Domino Michael/Acyl Transfer Reaction Between α-Nitroketones and in situ-Generated ortho-Quinone Methides: Route to 2-(1-Arylethyl)phenols
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An organocatalytic asymmetric domino Michael/acyl transfer reaction between α-nitroketones and o-quinone methides is disclosed. o-Quinone methides are generated in situ from 2-sulfonylmethylphenols in basic medium. With 10 mol% of bifunctional squaramide catalyst, high yields and excellent enantioselectivities are achieved for a variety of O-acyl 2-(1-arylethyl)phenols under mild reaction condition. (Figure presented.).
- Gharui, Chandan,Behera, Debasmita,Pan, Subhas Chandra
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supporting information
p. 4502 - 4508
(2018/11/10)
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- A simple synthesis of benzofurans by acid-catalyzed domino reaction of salicyl alcohols with N-tosylfurfurylamine
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A simple route to polysubstituted benzofurans based on the domino reaction of commercial or easily available salicyl alcohols with N-protected furfurylamine has been designed and developed. The reaction was found to proceed with reasonable yields under heating of substrates in acetic acid in the presence of catalytic amount of conc. HCl when tosyl was used as protecting group.
- Merkushev, Anton A.,Strel'nikov, Vladimir N.,Uchuskin, Maxim G.,Trushkov, Igor V.
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p. 6523 - 6529
(2017/10/17)
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- Multicomponent Condensation Reactions via ortho-Quinone Methides
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Iron(III) salts promote the condensation of aldehydes or acetals with electron-rich phenols to generate ortho-quinone methides that undergo Diels - Alder condensations with alkenes. The reaction sequence occurs in a single vessel to afford benzopyrans in up to 95% yield. The reaction was discovered while investigating a two-component strategy using 2-(hydroxy(phenyl)methyl)phenols to access the desired ortho-quinone methide in a Diels - Alder condensation. The two-component condensation also afforded the corresponding benzopyran products in yields up to 97%. Taken together, the two- and three-component strategies using ortho-quinone methide intermediates provide efficient access to benzopyrans in good yields and selectivities.
- Allen, Emily E.,Zhu, Calvin,Panek, James S.,Schaus, Scott E.
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supporting information
p. 1878 - 1881
(2017/04/11)
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- Organocatalytic Phosphonylation of in Situ Formed o-Quinone Methides
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A new class of Br?nsted acid catalysts based on N-heterocyclic phosphorodiamidic acids (NHPAs) has been developed. The NHPA catalyst promotes phospha-Michael addition reaction of trialkylphosphites to in situ generated ortho-quinone methides (o-QMs) for t
- Huang, Hai,Kang, Jun Yong
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supporting information
p. 5988 - 5991
(2017/11/10)
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- Bifunctional Amine-Squaramide Catalyzed Friedel–Crafts Alkylation Based on ortho-Quinone Methides in Oil-Water Phases: Enantioselective Synthesis of Triarylmethanes
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An efficient enantioselective Friedel–Crafts alkylation reaction of electron-rich β-naphthol with in situ generated ortho-quinone methides catalyzed by chiral bifunctional amine-squaramide catalysts has been developed. The chiral triarylmethane derivative
- Wang, Yifeng,Zhang, Cheng,Wang, Haojiang,Jiang, Yidong,Du, Xiaohua,Xu, Danqian
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supporting information
p. 791 - 797
(2017/03/11)
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- Organocatalytic Asymmetric Nucleophilic Addition to o-Quinone Methides by Alcohols
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The first catalytic asymmetric intermolecular alcohol conjugate addition to o-quinone methides (o-QMs) is disclosed. Due to reversible C-O bond formation and low nucleophilicity of alcohols, catalytic asymmetric oxa-Michael additions with simple alcohol nucleophiles to establish acyclic oxygenated carbon stereocenters remain scarce. The present reaction represents a rare example of this type. With a suitable chiral acid catalyst, the in situ formation of o-QMs and subsequent conjugate addition proceeded with high efficiency and enantioselectivity. The chiral ether products are versatile precursors to other chiral molecules.
- Lai, Zengwei,Wang, Zhaobin,Sun, Jianwei
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supporting information
p. 6058 - 6061
(2016/01/09)
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- One-pot synthesis of 3,4-disubstituted coumarins under catalysis of Mn 3O4 nanoparticles
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The one-pot synthesis of 3,4-disubstituted coumarins from substituted 2-(hydroxymethyl)phenols with β-keto esters catalyzed by Mn 3O4 nanoparticles was developed. A series of 3,4-disubstituted coumarin derivatives were obtained in good yields. A new method for the one-pot synthesis of 3,4-disubstituted coumarins from substituted 2-(hydroxymethyl)phenols with β-keto esters catalyzed by Mn 3O4 nanoparticles has been developed. A series of 3,4-disubstituted coumarin derivatives were synthesized from substituted 2-(hydroxymethyl)phenols and β-keto esters in good yields. Copyright
- Sun, Huayin,Zhang, Yonghui,Guo, Fengfeng,Yan, Yizhe,Wan, Changfeng,Zha, Zhenggen,Wang, Zhiyong
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supporting information; experimental part
p. 480 - 483
(2012/03/09)
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- THE 2-(TRIMETHYLSILYL)ETHOXYMETHOXY (OSEM) DIRECTED ORTHO METALATION GROUP. NEW REGIOSPECIFIC SYNTHETIC ROUTES TO SUBSTITUTED BENZENES AND PYRIDINES
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Regiospecific routes to ortho-substituted phenols and 3-pyridinols have been developed using the OSEM Directed Metalation Group.
- Sengupta, Saumitra,Snieckus, Victor
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p. 4267 - 4270
(2007/10/02)
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- Mannich Bases, XXI: Exchange Reactions of Phenolic Mannich Bases
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Various p-substituted phenolic Mannich bases (and to a minor degree o-substituted derivatives) form alcohols and ethers when heated in aqueous alcohols in the presence of Na2EDTA or acetic acid.The reaction proceeds with amine elimination and subsequent addition of the solvent to the resulting quinone methide.
- Moehrle, Hans,Miller, Christoph
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p. 229 - 236
(2007/10/02)
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