- One-pot two-step sequential transformation: Highly efficient construction of o-2,3,5,6-tetrafluorobenzonitrile substituted oximes ethers
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A practical variety of o-2,3,5,6-tetrafluorobenzonitrile substituted oximes ethers bearing broad functional groups were synthesized in moderate to good yields. The key highlight of this disclosure involving a one-pot two-step tandem procedure in aqueous media: the in situ formation of aryl aldehydes or ketones oximes followed by the SNAr reaction with pentafluorobenzonitrile via the high selective CF bond cleavage.
- Liu, Cuibo,Yin, Xuguang,Chang, Jing,Tang, Xiangyang,Zhang, Bin
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Read Online
- C3-Arylation of indoles with aryl ketonesviaC-C/C-H activations
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C3-Arylation of indoles with aryl ketones is accomplishedviapalladium-catalyzed ligand-promoted Ar-C(O) cleavage and subsequent C-H arylation of indole. Various (hetero)aryl ketones are compatible in this reaction, affording the corresponding 3-arylindoles in moderate to good yields. Further introduction of an indole moiety into the natural products desoxyestrone and evodiamine demonstrate the synthetic utility of this protocol.
- Dai, Hui-Xiong,Guo, Zi-Qiong,Ma, Biao,Wang, Xing,Wang, Zhen-Yu,Xu, Hui
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supporting information
p. 9716 - 9719
(2021/09/30)
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- Copper-catalyzed synthesis of oxime ethers from iminoxy radical (C[dbnd]N–O[rad]) and maleimides via radical addition
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An efficient Cu(II)-catalyzed radical addition of maleimides has been achieved. The identified copper catalyst enables the formation of oxime radicals (N–O[rad]) by cleaving the O–H bond in ketoximes, followed by the radical addition to N-substituted male
- Han, Ziwei,Shen, Subo,Zheng, Feng,Hu, Han,Zhang, Jianmin,Zhu, Shizheng
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supporting information
(2019/09/30)
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- Cp?-Free Cobalt-Catalyzed C-H Activation/Annulations by Traceless N, O-Bidentate Directing Group: Access to Isoquinolines
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N,O-Bidentate directing-enabled, traceless heterocycle synthesis is described via Cp?-free cobalt-catalyzed C-H activation/annulation. The weakly coordinating nature of the carboxylic acid was employed for the preparation of isoquinolines. Meanwhile, the N-O bond of the α-imino-oxy acid can serve as an internal oxidant. Terminal as well as internal alkynes can be efficiently applied to the catalytic system. This operationally simple approach shows a broad substrate scope with the products obtained in good to excellent yields.
- Li, Xiao-Cai,Du, Cong,Zhang, He,Niu, Jun-Long,Song, Mao-Ping
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supporting information
p. 2863 - 2866
(2019/04/17)
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- Dichloroimidazolidinedione-Activated Beckmann Rearrangement of Ketoximes for Accessing Amides and Lactams
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A novel protocol for the activation of the Beckmann rearrangement utilizing the readily available and economical geminal dichloroimidazolidinediones (DCIDs) on a substoichiometric scale (10 mol %) has been developed. A unique self-propagating mechanism for the substoichiometric dichloroimidazolidinedione-activated transformation was proposed and validated. The substrate scope of the developed protocol has been demonstrated by 23 examples with good to excellent yields (mostly 90-98%) in a short time (mostly 10-30 min), including a substrate for synthesizing the monomer of nylon-12 and a complicated steroidal substrate on a preparative scale. This research not only unveils for the first time the synthetic potential of substoichiometric amounts of dichloroimidazolidinediones in promoting chemical transformation but also offers yet another important illustration of the self-propagating cycle in the context of the Beckmann rearrangement activated by a structurally novel organic promoter.
- Gao, Yu,Liu, Jingjing,Li, Zhenjiang,Guo, Tianfo,Xu, Songquan,Zhu, Hui,Wei, Fulan,Chen, Siming,Gebru, Hailemariam,Guo, Kai
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p. 2040 - 2049
(2018/02/23)
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- Novel chemoenzymatic oxidation of amines into oximes based on hydrolase-catalysed peracid formation
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The efficient transformation of benzylamines into the corresponding oximes has been described by means of a chemoenzymatic process. This strategy is based on a two-step sequence developed in one-pot at 30 °C and atmospheric pressure. First, the formation of a reactive peracid intermediate occurs by means of a lipase-catalysed perhydrolysis reaction, and then this peracid acts as a chemical oxidising agent of the amines. A total of nine ketoximes were isolated in high purity after a simple extraction protocol (90-98% isolated yield), while for the eleven synthesised aldoximes a further column chromatography purification was required (71-82% isolated yield). In all cases excellent selectivities were attained, offering a practical method for amine oxidation in short reaction times (1 hour). The environmental impact of the process was analysed and compared with a recently published alternative chemical synthesis, finding for this metric a good E-factor value.
- Méndez-Sánchez, Daniel,Lavandera, Iván,Gotor, Vicente,Gotor-Fernández, Vicente
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p. 3196 - 3201
(2017/04/21)
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- Asymmetric synthesis of nonracemic primary amines via spiroborate-catalyzed reduction of pure (E)- and (Z)-O-benzyloximes: Applications toward the synthesis of calcimimetic agents
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Highly enantiopure (1-aryl)- and (1-naphthyl)-1-ethylamines were synthesized by the borane-mediated reduction of single-isomeric (E)- and (Z)-O-benzyloxime ethers using the stable spiroborate ester derived from (S)-diphenyl valinol and ethylene glycol as the chiral catalyst. Primary (R)-arylethylamines were prepared by the reduction of pure (Z)-ethanone oxime ethers in up to 99% ee using 15% of catalyst. Two convenient and facile approaches to the synthesis of new and known calcimimetic analogues employing enantiopure (1-naphthalen-1-yl)ethylamine as chiral precursor are described.
- Ou, Wenhua,Espinosa, Sandraliz,Meléndez, Héctor J.,Farré, Silvia M.,Alvarez, Jaime L.,Torres, Valerie,Martínez, Ileanne,Santiago, Kiara M.,Ortiz-Marciales, Margarita
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p. 5314 - 5327
(2013/07/25)
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- Enantioselective reduction of ketoxime ethers with borane-oxazaborolidines and synthesis of the key intermediate leading to (S)-rivastigmine
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The reduction of representative alkyl aryl (E)-ketoxime O-benzyl ethers with borane catalyzed by terpene oxazaborolidines, derived from (1R)-nopinone and (1R)-camphor, gave the corresponding amines with 82-99% ee. Oxazaborolidines derived from (1S)-2-carene and (1S)-3-carene were less selective. (S)-1-(3-Methoxyphenyl)ethanamine (94% ee) the key intermediate in the synthesis of (S)-rivastigmine, was obtained by the reduction of (E)-1-(3-methoxyphenyl) ethanone O-benzyl oxime with borane/oxazaborolidine generated from (S)-valinol.
- Pakulski, Marcin M.,Mahato, Sanjit K.,Bosiak, Mariusz J.,Krzeminski, Marek P.,Zaidlewicz, Marek
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experimental part
p. 716 - 721
(2012/09/21)
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- A process for the preparation of rivastigmine or a salt thereof
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There are provided processes for making rivastigmine. In one embodiment, the process includes reacting S-(-)-[1-(3-hydroxyphenyl)ethyl]dimethylamine with N-ethyl-N-methyl carbamoyl chloride in the presence of an organic base to obtain a free base of rivastigmine.
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Page/Page column 12
(2008/12/04)
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- PREPARATION OF RIVASTIGMINE AND ITS SALTS
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There are provided processes for making rivastigmine. In one embodiment, the process includes reacting S-(?)-[1-(3-hydroxyphenyl)ethyl]dimethylamine with N-ethyl-N-methyl carbamoyl chloride in the presence of an organic base to obtain a free base of rivastigmine.
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Page/Page column 8
(2008/12/04)
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- Enantioselective Strecker-type reaction of phosphinoyl ketimines catalyzed by a chiral Zr-bipyridyldiol catalyst
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An enantioselective Strecker reaction of N-diphenylphosphinoyl ketimines with TMSCN employing a chiral zirconium complex formed from chiral bipyridyl diol 1 as catalyst is described. The catalytic efficiency of chiral ligand 1 with other Lewis acids was also explored. Higher yields (50-85%) with moderate to good enantioselectivities (30-80%) were achieved for a variety of N-diphenylphosphinoyl ketimines.
- Chen, Yi-Jing,Chen, Chinpiao
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experimental part
p. 2201 - 2209
(2009/04/05)
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- Mercury-catalyzed rearrangement of ketoximes into amides and lactams in acetonitrile
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(Chemical Equation Presented) An acetonitrile solution of mercury(II) chloride has been found to catalyze efficiently the conversion of a diverse range of ketoximes into their corresponding amides/lactams.
- Ramalingan, Chennan,Park, Yong-Tae
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p. 4536 - 4538
(2008/02/04)
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- Cyanuric chloride as a mild and active Beckmann rearrangement catalyst
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The first general organocatalytic Beckmann rearrangement of ketoximes into amides has been realized by the catalytic use of cyanuric chloride. Furthermore, acids such as HCl and ZnCl2 are effective as cocatalysts with cyanuric chloride. For example, azacyclotridecan-2-one, which is synthetically useful as a starting material for nylon-12, was prepared in quantitative yield by the Beckmann rearrangement of cyclododecanone oxime (100 mmol scale) catalyzed by cyanuric chloride (0.5 mol %) and ZnCl2 (1 mol %). Copyright
- Furuya, Yoshiro,Ishihara, Kazuaki,Yamamoto, Hisashi
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p. 11240 - 11241
(2007/10/03)
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- APO AI EXPRESSION ACCELERATING AGENT
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Pharmaceutical compositions for enhancing the expression of apoAI are provided.Pharmaceutical compositions for enhancing the expression of apoAI which comprises a compound of formula (I): in which Y1 is O, S or NR1; Y2, Y
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