- Catalyst- and acid-free Markovnikov hydration of alkynes in a sustainable H2O/ethyl lactate system
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An efficient and sustainable protocol for the hydration of alkynes has been developed under metal/acid/catalyst/ligand-free conditions in a water/ethyl lactate mixture. The hydrogen-bond network in the ethyl lactate and water mixture plays a crucial and decisive role in activating the alkynes for hydration to afford the corresponding methyl ketones. This strategy gives the Markovnikov (ketone) addition product selectively over other possible products. The essential role of hydrogen bonding has been confirmed by experimental and theoretical techniques. A probable mechanism has been suggested by various control tests. The efficacy of the method has been further explored for the competent production of value-added α,β-unsaturated carbonyl compounds through the reaction of aldehydes with alkynes as ketonic surrogates. The environmentally benign hydration method takes place under mild conditions, has broad functional-group compatibility, and uses the ethyl lactate/water (1:3) medium as a “green alternative” in the absence of any hazardous, harmful, or expensive substances.
- Dandia, Anshu,Saini, Pratibha,Chithra,Vennapusa, Sivaranjana Reddy,Parewa, Vijay
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- The intramolecular reaction of acetophenoneN-tosylhydrazone and vinyl: Br?nsted acid-promoted cationic cyclization toward polysubstituted indenes
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In the presence of TsNHNH2, a Br?nsted acid-promoted intramolecular cyclization ofo-(1-arylvinyl) acetophenone derivatives was developed, leading to polysubstituted indenes with complexity and diversity in moderate to excellent yields. In sharp contrast with either the radical or carbene involved cyclization of aldehydicN-tosylhydrazone with vinyl, a cationic cyclization pathway was involved, whereN-tosylhydrazone served as an electrophile and alkylation reagent during this transformation.
- Wang, Zhixin,Li, Yang,Chen, Fan,Qian, Peng-Cheng,Cheng, Jiang
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supporting information
p. 1810 - 1813
(2021/02/27)
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- α-Oxocarboxylic Acids as Three-Carbon Insertion Units for Palladium-Catalyzed Decarboxylative Cascade Synthesis of Diverse Fused Heteropolycycles
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A novel palladium-catalyzed decarboxylative cascade cyclization for the assembly of diverse fused heteropolycycles by employing α-oxocarboxylic acids as three-carbon insertion units is reported. This protocol enables the synthesis of isoquinolinedione- and indolo[2,1-a]isoquinolinone-fused benzocycloheptanones in moderate to good yields by the use of different aryl iodides, including alkene-tethered 2-iodobenzamides and 2-(2-iodophenyl)-1H-indoles. Notably, the approach achieves simultaneous construction of both six- and seven-membered rings via sequential intramolecular carbopalladation, C-H activation, and decarboxylation.
- Zhou, Liwei,Qiao, Shujia,Zhou, Fengru,Xuchen, Xinyu,Deng, Guobo,Yang, Yuan,Liang, Yun
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supporting information
p. 2878 - 2883
(2021/05/05)
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- Atmosphere-Controlled Palladium-Catalyzed Divergent Decarboxylative Cyclization of 2-Iodobiphenyls and α-Oxocarboxylic Acids
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A novel palladium-catalyzed divergent decarboxylative cyclization of 2-iodobiphenyls and α-oxocarboxylic acids utilizing the atmosphere as a controlled switch is reported. Under the protection of a nitrogen atmosphere, tribenzotropones are synthesized by a [4 + 3] decarboxylative cyclization. Employing a palladium/O2 system enables a [4 + 2] decarboxylative cyclization to assemble triphenylenes. Notably, preliminary mechanistic studies indicate that the formation of triphenylenes involves a double decarboxylation.
- Zhou, Liwei,Sun, Mingjie,Zhou, Fengru,Deng, Guobo,Yang, Yuan,Liang, Yun
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supporting information
p. 7150 - 7155
(2021/09/18)
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- Divergent Access to Benzocycles through Copper-Catalyzed Borylative Cyclizations
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A copper-catalyzed chemodivergent approach to five- and six-membered benzocycles from dienyl arenes tethered with a ketone has been developed. Through proper choice of coordinating ligands and catalytic conditions, copper-catalyzed borylative cyclization of a single dienyl arene can be diverted to two different pathways, leading to indanols and dihydronaphthalenols with high stereoselectivity. The chiral bidentate bisphosphine ligand (S,S)-Ph-BPE was optimal for asymmetric copper-allyl addition to a tethered ketone via a boat-like transition state, whereas NHC ligands led to boro-allyl addition producing indanols with high diastereoselectivity. (Figure presented.).
- Yoon, Wan Seok,Han, Jung Tae,Yun, Jaesook
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supporting information
p. 4953 - 4959
(2021/09/14)
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- Asymmetric Synthesis and Application of Chiral Spirosilabiindanes
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Reported here is the development of a class of chiral spirosilabiindane scaffolds by Rh-catalyzed asymmetric double hydrosilation, for the first time. Enantiopure SPSiOL (spirosilabiindane diol), a new type of chiral building block for the preparation of various chiral ligands and catalysts, was readily prepared on greater than 10 gram scale using this protocol. The potential of this new spirosilabiindane scaffold in asymmetric catalysis was preliminarily demonstrated by development of the corresponding monodentate phosphoramidite ligands (SPSiPhos), which were used in both a Rh-catalyzed hydrogenation and a Pd-catalyzed intramolecular carboamination.
- Chang, Xin,Chen, Hong-Chao,Li, Chuan-Ying,Ma, Pei-Long,Wang, Peng
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supporting information
p. 8937 - 8940
(2020/04/30)
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- Acceptorless dehydrogenation of amines and alcohols using simple ruthenium chloride
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A highly efficient, economic and environmental friendly catalyst system has been developed for the dehydrogenation of alcohols and amines using simple RuCl3·nH2O and N-benzylhexamethylenetetramine. The in situ catalyst system efficiently oxidized the primary and secondary amines and secondary alcohols into nitrile, imine and ketone products, respectively in moderate to excellent yields. The developed catalyst system was also found to be efficient for the dehydrogenation of N-heterocyles. A detailed mechanism study revealed the first example of N-benzylhexamethylenetetramine (HMTA-Bz) being simultaneously acting as base, reducing agent and hydride source to generate the [Ru(II)(H)2] species as the active catalyst. The mechanism studies also revealed both the alcohol and amine oxidation involves dehydrogenative pathway with the evolution of hydrogen as the only by-product. The developed catalyst system also provides possible platform for the release of hydrogen from liquid organic hydrogen carriers (LOHCs).
- Barteja, Parul,Devi, Preeti,Kannan, Muthukumar,Muthaiah, Senthilkumar
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- Asymmetric Synthesis of 1,2-Dihydronaphthalene-1-ols via Copper-Catalyzed Intramolecular Reductive Cyclization
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We describe a copper-catalyzed intramolecular reductive cyclization of easily accessible benz-tethered 1,3-dienes containing a ketone moiety. This process provided biologically active 1,2-dihydronaphthalene-1-ol derivatives in good yields with excellent enantio- and diastereoselectivity. Mechanistic investigations using density functional theory revealed that (Z)- and (E)-allylcopper intermediates formed in situ from the diene and copper catalyst undergo isomerization and selective intramolecular allylation of the (E)-allylcopper form of the major product through a six-membered boatlike transition state. The resulting products were further transformed to fully saturated naphthalene-1-ols by reactions of the olefin moiety.
- Acharyya, Ranjan Kumar,Kim, Soyoung,Park, Yeji,Han, Jung Tae,Yun, Jaesook
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supporting information
p. 7897 - 7902
(2020/11/02)
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- PdII-Catalyzed Oxidative Tandem aza-Wacker/Heck Cyclization for the Construction of Fused 5,6-Bicyclic N,O-Heterocycles
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A PdII-catalyzed oxidative tandem cyclization was developed for the construction of fused 5,6-bicyclic N, O-heterocycles. This reaction was enabled by the combined use of a 3-methylpyridine ligand and pentafluorobenzoic acid additive. A range of heterocyclic products with different substituents could be prepared in moderate to good yields via this methodology. Several transformations, including a scaled-up preparation of product 2 a, were also carried out showing the good applicability of our methodology.
- Ye, Chenghao,Kou, Xuezhen,Xia, Jingzhao,Yang, Guoqiang,Kong, Li,Wei, Quhao,Zhang, Wanbin
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supporting information
p. 1897 - 1901
(2018/07/31)
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- One-Pot Asymmetric Synthesis of Alkylidene 1-Alkylindan-1-ols Using Br?nsted Acid and Palladium Catalysis
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A one-pot catalytic enantioselective allylboration/Mizoroki-Heck reaction of 2-bromoaryl ketones has been developed for the asymmetric synthesis of 3-methyleneindanes bearing a tertiary alcohol center. Br?nsted acid-catalyzed allylboration with a chiral BINOL derivative was followed by a palladium-catalyzed Mizoroki-Heck cyclization, resulting in selective formation of the exo-alkene. This novel protocol provides a concise and scalable approach to 1-alkyl-3-methyleneindan-1-ols in high enantiomeric ratios (up to 96:4 er). The potential of these compounds as chiral building blocks was demonstrated with efficient transformation to optically active diol and amino alcohol scaffolds.
- Faggyas, Réka J.,Calder, Ewen D. D.,Wilson, Claire,Sutherland, Andrew
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p. 11585 - 11593
(2017/11/10)
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- Enantioselective Bromo-oxycyclization of Silanol
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Relying on the nucleophilicity of silanol for building up silicon-incorporated scaffold with an enantiopure tetrasubstituted carbon center remains elusive. In this report, asymmetric bromo-oxycyclization of olefinic silanol by using chiral anionic phase-transfer catalyst is described. This protocol provided a facile entry to a wide arrangement of enantiopure benzoxasilole in moderate to excellent enantioselectivities depending on the unique reactivity of bromine/N-benzyl-DABCO complex.
- Xia, Zilei,Hu, Jiadong,Shen, Zhigao,Wan, Xiaolong,Yao, Qizheng,Lai, Yisheng,Gao, Jin-Ming,Xie, Weiqing
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supporting information
p. 80 - 83
(2016/01/15)
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- Facile synthesis of 1-naphthols through a copper-catalyzed arylation of methyl ketones with o-bromoacetophenones
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The coupling reactions of simple methyl ketones with o-bromoacetophenones and subsquential cyclization reactions were realized to produce a range of 1-naphthols. These cascade reactions were initiated by a rare Cu-catalyzed arylation reaction of methyl ketones with aromatic bromides.
- Lou, Zhen-Bang,Pang, Xin-Long,Chen, Chao,Wen, Li-Rong,Li, Ming
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supporting information
p. 1231 - 1235
(2015/12/30)
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- Soluble ferrocene conjugates for incorporation into self-assembled monolayers
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A series of phenylethynyl oligomers (I-V) possessing a ferrocene and thiol at each termini have been synthesized. These oligomers have been designed to overcome the inherent insolubility of this class of complexes by substitution at the phenyl groups with methyl and propoxy substituents. Several new reactions for preparing arenethiol-protected compounds are described. Interestingly, the generation of an arenethiol anion during base- or fluoride-catalyzed deprotection has been characterized.
- Yu,Chong, Yoochul,Kayyem, Jon Faiz,Gozin, Michael
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p. 2070 - 2079
(2007/10/03)
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- The Synthesis of Two Benzodiisothiazoles
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Two benzodiisothiazoles, 8-methyldiisothiazole and 3-methylbenzodiisothiazole, have been made by reaction of appropriate aminomethyl-1,2-benzisothiazoles with N-sulfinylmethanesulfonamide.
- McKinnon, David M.,Abouzeid, Azza
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p. 347 - 350
(2007/10/02)
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