- Synthesis of 25X-BOMes and 25X-NBOHs (X = H, I, Br) for pharmacological studies and as reference standards for forensic purposes
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An expeditious method is reported for the synthesis of three NBOHs (25H-, 25I- and 25B-NBOH; 9–38% overall yield) and three NBOMes (25H-, 25I- and 25B-NBOMe; 7–33% overall yield) from salicylaldehyde and 2-methoxyaldehyde, respectively. The X-ray structures of 25H-, 25I- and 25B-NBOH.HCl were also determined. Our approach should provide a general entry for preparing such a class of substances for pharmacological and forensic purposes.
- Alves de Barros, Wellington,Queiroz, Marcelo Pereira,da Silva Neto, Leonardo,Borges, Graziele Martins,Martins, Felipe Terra,de Fátima, ?ngelo
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- Production of (S)-β-Nitro Alcohols by Enantioselective C?C Bond Cleavage with an R-Selective Hydroxynitrile Lyase
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Hydroxynitrile lyase (HNL)-catalysed stereoselective synthesis of β-nitro alcohols from aldehydes and nitroalkanes is considered an efficient biocatalytic approach. However, only one S-selective HNL—Hevea brasiliensis (HbHNL)—exists that is appropriate for the synthesis of (S)-β-nitro alcohols from the corresponding aldehydes. Further, synthesis catalysed by HbHNL is limited by low specific activity and moderate yields. We have prepared a number of (S)-β-nitro alcohols, by kinetic resolution with the aid of an R-selective HNL from Arabidopsis thaliana (AtHNL). Optimization of the reaction conditions for AtHNL-catalysed stereoselective C?C bond cleavage of racemic 2-nitro-1-phenylethanol (NPE) produced (S)-NPE (together with benzaldehyde and nitromethane, largely from the R enantiomer) in up to 99 % ee and with 47 % conversion. This is the fastest HNL-catalysed route known so far for the synthesis of a series of (S)-β-nitro alcohols. This approach widens the application of AtHNL for the synthesis not only of (R)- but also of (S)-β-nitro alcohols from the appropriate substrates. Without the need for the discovery of a new enzyme, but rather by use of a retro-Henry approach, it was used to generate a number of (S)-β-nitro alcohols by taking advantage of the substrate selectivity of AtHNL.
- Rao, D. H. Sreenivasa,Padhi, Santosh Kumar
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p. 371 - 378
(2019/01/08)
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- Salen-Based Covalent Organic Framework
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The Salen unit represents one of the most important ligands in coordination chemistry. We report herein the first example of a Salen-based covalent organic framework (COF), in which both the construction of the COF structure and the functionalization with Salen moieties have been realized in a single step. Due to its structural uniqueness, the obtained COF material, Salen-COF, possesses high crystallinity and excellent stability. Based on this, a series of metallo-Salen-based COFs were prepared via metalation for further applications.
- Li, Li-Hua,Feng, Xiao-Lin,Cui, Xiao-Hui,Ma, Yun-Xiang,Ding, San-Yuan,Wang, Wei
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supporting information
p. 6042 - 6045
(2017/05/09)
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- Preparation method of 1-(2,5-dimethoxy phenyl)-2-aminoethanol
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The invention provides a preparation method of hydrochloric acid midodrine intermediate 1-(2,5-dimethoxy phenyl)-2-aminoethanol, comprising the steps of adopting 2,5-dimethoxy benzaldehyde as the raw material to condense with nitromethane under the effect of alkali to obtain 1-(2,5-dimethoxy phenyl)-2-nitroethanol, reducing 1-(2,5-dimethoxy phenyl)-2-nitroethanol with a boron reductant to obtain 1-(2,5-dimethoxy phenyl)-2-aminoethanol. The preparation method of 1-(2,5-dimethoxy phenyl)-2-aminoethanol has the advantages of being mild in reaction conditions, simple in the operation process, high in yield, environment-friendly and low in production cost, and is applicable to industrial production.
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Paragraph 0032-0034
(2017/03/08)
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- (2S,5R)-2-Methylaminomethyl-1-methyl-5-phenylpyrrolidine, a chiral diamine ligand for copper(ii)-catalysed Henry reactions with superb enantiocontrol
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A cis-2-aminomethyl-5-phenylpyrrolidine, which is easily available from methyl Boc-l-pyroglutamate, was found to be a highly efficient chiral ligand for Cu(ii)-catalysed Henry reactions. Excellent yields (>90%) and superb levels of enantiocontrol (98.5-99.6% ee) were reached with aromatic, heteroaromatic, vinylic, and aliphatic aldehydes (36 examples). This journal is the Partner Organisations 2014.
- Scharnagel, Dagmar,Prause, Felix,Kaldun, Johannes,Haase, Robert G.,Breuning, Matthias
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supporting information
p. 6623 - 6625
(2014/06/10)
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- Asymmetric Henry reaction catalyzed by Cu(I)-based chiral amino alcohol complex
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The Cu(I)-based complex prepared from (S)-2-(furan-2-yl-methylamino)-2- phenylethanol (5c) and CuCl was used as catalyst in enantioselective Henry reactions of arylaldehydes and nitromethane, which gave 89% ee and 95% yield at ambient temperature. The proposed catalytic cycle of an asymmetric Henry reaction was suggested. TUeBITAK.
- Shen, Tianhua,Qin, Quan,Ni, Hang,Xia, Ting,Zhou, Xiaocong,Cui, Funa,Li, Junqi,Ran, Deqiang,Song, Qingbao
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p. 966 - 977
(2013/12/04)
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- Crown ether complex cation ionic liquids: Preparation and applications in organic reactions
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A series of crown ether complex cation ionic liquids (CECILs) were designed, synthesised and characterised by NMR spectroscopy, HRMS, thermogravimetric differential thermal analysis (TG-DTA) and elemental analysis. Their applications in various organic reactions were investigated: [15-C-5Na][OH], [15-C-5Na][OAc], [18-C-6K][OH] and [18-C-6K][OAc] (15-C-5=[15]crown-5; 18-C-6=[18]crown-6) efficiently catalysed the Michael addition of alkenes and relevant nucleophiles; [18-C-6K][OH] and [15-C-5Na][OH] effectively catalysed the Henry reaction of nitromethane and aromatic aldehydes; [18-C-6K][OH] has excellent catalytic efficiency for Knoevenagel condensation of aromatic aldehydes and malononitrile; PdCl2/[18-C-6K] 3[PO4]/K2CO3 efficaciously catalysed the Heck reaction of olefins and aromatic halides; [18-C-6K][BrO3] can be used as both oxidant and solvent in the oxidation reaction of aromatic alcohols. The CECIL catalysts [15-C-5Na][OH] (Michael addition) and [18-C-6K][OH] (Henry reaction) can be recycled and reused several times without obvious loss of activity and their recovery is very simple.
- Song, Yingying,Jing, Huanwang,Li, Bo,Bai, Dongsheng
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experimental part
p. 8731 - 8738
(2011/09/16)
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- Heterogeneous catalysts in the preparation of 2-aryl-1,3-dinitropropanes from β-nitrostyrenes or benzaldehydes
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The use of heterogeneous basic catalysts (KF, NaHCO3) in the preparation of 2-Aryl-1,3-dinitropropanes from β-nitrostyrenes or benzaldehydes is described, with one example followed kinetically by HPLC analysis of aliquots of the reaction.
- Fierro,Rezende,Sepulveda-Boza,Reyes-Parada,Cassels
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p. 294 - 296
(2007/10/03)
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