18278-24-5Relevant academic research and scientific papers
Deracemization through photochemical E/Z isomerization of enamines
Huang, Mouxin,Luo, Sanzhong,Pan, Tianrun,Zhang, Long
, p. 869 - 874 (2022/03/07)
Catalytic deracemization of a-branched aldehydes is a direct strategy to construct enantiopure a-tertiary carbonyls, which are essential to pharmaceutical applications. Here, we report a photochemical E/Z isomerization strategy for the deracemization of a-branched aldehydes by using simple aminocatalysts and readily available photosensitizers. A variety of racemic a-branched aldehydes could be directly transformed into either enantiomer with high selectivity. Rapid photodynamic E/Z isomerization and highly stereospecific iminium/enamine tautomerization are two key factors that underlie the enantioenrichment. This study presents a distinctive photochemical E/Z isomerization strategy for externally tuning enamine catalysis.
Palladium/TY-Phos-Catalyzed Asymmetric Intermolecular α-Arylation of Aldehydes with Aryl Bromides
Li, Wenbo,Liu, Feng,Pan, Zhangjin,Wu, Hai-Hong,Zhang, Junliang,Zhu, Shuai
, p. 18542 - 18546 (2021/07/21)
Despite much progress has been made in the asymmetric α-arylation reactions of cyclic ketones, lactones and lactams, the enantioselective α-arylation of acyclic carbonyl compounds lagged much behind due to the in situ generated Z/E-enolate intermediates l
Palladium-Catalyzed Allenamide Carbopalladation/Allylation with Active Methine Compounds
Zhu, Xiaoyi,Li, Ruibo,Yao, Hequan,Lin, Aijun
supporting information, p. 4630 - 4634 (2021/06/28)
A palladium-catalyzed allenamide carbopalladation/allylation with active methine compounds has been developed. Various indoles and isoquinolinones bearing a quaternary carbon center were achieved with good efficiency, a broad substrate scope and good functional group tolerance. This reaction underwent cascade oxidative addition, carbopalladation, and allylic alkylation, and two new C-C bonds were formed in one pot.
Hydrochloric acid palonosetron and intermediate preparation method (by machine translation)
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Paragraph 0078; 0081; 0082; 0083; 0084, (2018/07/07)
The invention discloses hydrochloric acid palonosetron and intermediate preparation method. The invention provides a preparation method of palonosetron intermediate I, comprises the following steps: in the organic solvent, the presence of a reducing agent, the compound III with the S - 3 - amino quinine cyclic amine reaction of intermediate I Sparrow division of the agar. The invention palonosetron preparation method of the midbody mild reaction conditions, post-processing step is simple, safe operation, the total yield is high, the prepared product has high purity, low production cost, the atom utilization rate is high, and is suitable for industrial production; and palonosetron intermediates of the present invention can be prepared in accordance with the raw materials of the standard of the hydrochloric acid palonosetron. (by machine translation)
Cobalt-Catalyzed Diborylation of 1,1-disubstituted Vinylarenes: A Practical Route to Branched gem-Bis(boryl)alkanes
Teo, Wei Jie,Ge, Shaozhong
supporting information, p. 1654 - 1658 (2018/01/15)
We report the first catalytic diborylation of 1,1-disubstituted vinylarenes with pinacolborane using a cobalt catalyst generated from bench-stable Co(acac)2 and xantphos. A wide range of 1,1-disubstituted vinylarenes underwent this transformati
Oxidative rearrangement of alkenes using in situ generated hypervalent iodine(III)
Ahmad, Anees,Scarassati, Paulo,Jalalian, Nazli,Olofsson, Berit,Silva Jr., Luiz F.
supporting information, p. 5818 - 5820 (2013/10/01)
A novel protocol for the oxidative rearrangement of alkenes using in situ generated hypervalent iodine(III) was developed. This approach uses inexpensive, readily available, and stable chemicals (PhI, mCPBA, and TsOH) giving rearrangement products in yields comparable to those obtained using the more expensive commercially available [hydroxy(tosyloxy)iodo]benzene [HTIB or Koser's reagent]. Additionally, an alternative protocol for the synthesis of 1-methyl-2-tetralone through the one-step epoxidation/rearrangement of 4-methyl-1,2-dihydronaphthalene using mCPBA and TsOH was developed.
Synthesis and biological activity of both enantiomers of kujigamberol isolated from 85-million-years-old Kuji amber
Ye, Yue Qi,Koshino, Hiroyuki,Hashizume, Daisuke,Minamikawa, Yuki,Kimura, Ken-Ichi,Takahashi, Shunya
, p. 4259 - 4262 (2012/09/22)
The full-structure of a norlabdane terpenoid, kujigamberol (1) was determined by total synthesis. Key features of the total synthesis are (1) installation of isopentyl group through an o-lithiation of benzamide, (2) construction of tetralone by the RCM reaction, and (3) optical resolution of (±)-1 using chromatographical separation of the corresponding camphanates. X-ray crystallographical analysis of p-bromobenzoate obtained from the more polar camphanate that was identical with a natural derivative, revealed natural kujigamberol to have an S-configuration. Both the natural enantiomer and its (R)-antipode showed the same inhibitory activity toward the mutant yeast and HL-60 cells, while simple analogs without alkyl groups at the C-8 and 9 positions of (±)-1 had no such activity.
Oxidative cleavage of α-aryl aldehydes using iodosylbenzene
Havare, Nizam,Plattner, Dietmar A.
supporting information, p. 5078 - 5081,4 (2020/09/15)
We found that α-aryl aldehydes can be cleaved to chain-shortened carbonyl compounds and formaldehyde by various iodosylbenzene complexes. A mechanistic scheme is presented that accounts for the loss of one carbon atom. Formaldehyde is further oxidized to CO and CO2 under the reaction conditions.
Enantioselective synthesis of allenecarboxylates from phenyl acetates through C-C bond forming reactions
Yamazaki, Jiro,Watanabe, Toshiyuki,Tanaka, Kiyoshi
, p. 669 - 675 (2007/10/03)
A variety of optically active 4,4-disubstituted allenecarboxylic acid methyl esters were prepared from simple α,α-disubstituted phenyl acetate through base treatment of the esters to generate ketenes, followed by successive Horner-Wadsworth-Emmons reaction. The transformation was further developed as a one-pot procedure with satisfactory yields and high enantioselectivity.
2-substituted-(2SR)-2-amino-2-((1SR,2SR)-2-carboxycycloprop-1- yl)glycines as potent and selective antagonists of group II metabotropic glutamate receptors. 1. Effects of alkyl, arylalkyl, and diarylalkyl substitution
Ornstein, Paul L.,Bleisch, Thomas J.,Arnold, M. Brian,Wright, Rebecca A.,Johnson, Bryan G.,Schoepp, Darryle D.
, p. 346 - 357 (2007/10/03)
In this paper, we describe the synthesis of a series of α-substituted analogues of the potent and selective group II metabotropic glutamate receptor (mGluR) agonist (1S,1'S,2'S)-carboxy-cyclopropylglycine (2, L-CCG 1). Incorporation of a substituent on the amino acid carbon converted the agonist 2 into an antagonist. All of the compounds were prepared and tested as a aeries of four isomers, i.e., two racemic diastereomers. We explored alkyl substitution, both normal and terminally branched; phenylalkyl and diphenylalkyl substitution; and a variety of aromatic and carbocyclic surrogates for phenyl. Affinity for group II mGluRs was measured using [3H]glutamic acid (Glu) binding in rat forebrain membranes. Antagonist activity was confirmed for these compounds by measuring their ability to antagonize (1S,3R)-1-aminocyclopentane-1,3-dicarboxylic acid-induced inhibition of forskolin-stimulated cyclic-AMP in RGT cells transfected with human mGluR2 and mGluR3. We found that while alkyl substitution provided no increase in affinity relative to 2, phenylethyl and diphenylethyl substitution, as in 105 and 109, respectively, were quite beneficial. The affinity of 109 was further enhanced when the two aromatic rings were joined by an oxygen or sulfur atom to form the tricyclic xanthylmethyl and thioxanthylmethyl amino acids 113 and 114, respectively. Amino acid 113, with an IC50 of 0.010 μM in the [3H]Glu binding assay, was 52-fold more potent than 2, whose IC50 was 0.47 μM.
