4276-09-9Relevant academic research and scientific papers
A Spiroalkylation Method for the Stereoselective Construction of α-Quaternary Carbons and Its Application to the Total Synthesis of (R)-Puraquinonic Acid
Elmehriki, Adam A. H.,Gleason, James L.
supporting information, p. 9729 - 9733 (2019/12/02)
Cyclic α-quaternary carbon stereocenters were prepared from biselectrophillic substrates and an easily prepared chiral bicyclic sulfonyl lactam. This was achieved in two steps by spiroalkylation, employing biphasic reaction conditions with a phase-transfer catalyst, followed by reduction and alkylation with a series of alkyl halide electrophiles. The products of this method were isolated in good yields with with high levels of diastereoselectivity. This methodology was employed in the enantioselective total synthesis of (R)-puraquinonic acid (1) for a late-stage installation of the α-quaternary carbon stereocenter. This enabled the shortest synthesis of 1 to date, an eight-pot sequence providing an overall yield of 14%.
Heterogeneous Catalytic Hydrogenation of Chiral Amino Acid Methyl Esters to Amino Alcohols with Retention of Configuration Over Mg-Modified Cu/ZnO/Al2O3 Catalyst
Zhan, Bing,Zhang, Shuangshuang,Yu, Jun,Xiao, Xiuzheng,Guo, Xiaoming,Mao, Dongsen,Lu, Guanzhong
, p. 2160 - 2166 (2017/07/25)
Selective hydrogenation of amino acid methyl esters to chiral amino alcohols is an important and fascinating process. The CuZn0.3Mg0.1AlOx catalyst for the synthesis of chiral amino alcohols was prepared by the fractional
Total Enantioselective Synthesis of the Endophytic Fungal Polyketide Phomolide H and Its Structural Revision
McNulty, James,McLeod, David
supporting information, p. 29 - 33 (2017/01/14)
A total synthesis of the proposed structure of the natural polyketide-macrolactone phomolide H 2 has been achieved following a bidirectional strategy from l-tartaric acid. The originally assigned structure of phomolide H displayed discordant NMR spectroscopic data in comparison with synthetic 2. The synthetic strategy was extended to prepare diastereomers and epimeric methyl-ethers of the natural product, structural analysis of which revealed a match of the natural product with diastereomer 27. The structural revision of phomolide H from 2 to the methanol solvate of compound 27 is presented.
Enantioselective Total Synthesis of the Proposed Structure of the Endophytic Fungal Metabolite Phomolide G: Structural Revision and Unambiguous Stereochemical Assignment
McNulty, James,McLeod, David,Jenkins, Hilary A.
supporting information, p. 688 - 692 (2017/01/18)
A total synthesis of the proposed structure of the natural macrolactone phomolide G (1) by a bidirectional strategy from L-tartaric acid is reported. The ω-terminus of the molecule was elaborated by nitrile extension, C3-alkylation and a substrate-controlled 1,3-ketone reduction. The α-terminus was extended by a C2aldehyde-to-alkenal homologation followed by an auxiliary controlled aldol reaction. Macrolactonization and deprotection yielded compound 1 (confirmed by X-ray analysis). This putative structure of phomolide G displayed discordant NMR spectroscopic data in comparison with those of the natural product. Detailed inspection of all NMR spectroscopic data available indicated phomolide G to be likely a diastereomer of 1. The synthetic strategy developed allows control of the absolute stereochemistry at all four chiral secondary alcohol groups. Further manipulation allowed for the preparation of diastereomer 33, the1H and13C NMR spectroscopic data of which are in full accord with that reported for the natural product.
Design, Synthesis, Fungicidal Activity, and Unexpected Docking Model of the First Chiral Boscalid Analogues Containing Oxazolines
Li, Shengkun,Li, Dangdang,Xiao, Taifeng,Zhang, Shasha,Song, Zehua,Ma, Hongyu
, p. 8927 - 8934 (2016/12/07)
Chirality greatly influences the biological and pharmacological properties of a pesticide and will contribute to unnecessary environmental loading and undesired ecological impact. No structure and activity relationship (SAR) of enantiopure succinate dehydrogenase inhibitors (SDHIs) was documented during the structure optimization of boscalids. On the basis of commercial SDHIs, oxazoline natural products, and versatile oxazoline ligands in organic synthesis, the first effort was devoted to explore the chiral SDHIs and the preliminary mechanism thereof. Fine-tuning furnished chiral nicotinamides 4ag as a more promising fungicidal candidate against Rhizoctonia solani, Botrytis cinerea, and Sclerotinia sclerotiorum, with EC50 values of 0.58, 0.42, and 2.10 mg/L, respectively. In vivo bioassay and molecular docking were investigated to explore the potential in practical application and plausible novelty in action mechanism, respectively. The unexpected molecular docking model showed the different chiral effects on the binding site with the amino acid residues. This chiral nicotinamide also featured easy synthesis and cost-efficacy. It will provide a powerful complement to the commercial SDHI fungicides with the introduction of chirality.
Direct Generation of Triketide Stereopolyads via Merged Redox-Construction Events: Total Synthesis of (+)-Zincophorin Methyl Ester
Kasun, Zachary A.,Gao, Xin,Lipinski, Radoslaw M.,Krische, Michael J.
, p. 8900 - 8903 (2015/08/03)
(+)-Zincophorin methyl ester is prepared in 13 steps (longest linear sequence). A bidirectional redox-triggered double anti-crotylation of 2-methyl-1,3-propane diol directly assembles the triketide stereopolyad spanning C4-C12, significantly enhancing step economy and enabling construction of (+)-zincophorin methyl ester in nearly half the steps previously required.
Readily available ferrocenyl-phosphinite ligands for Ru(II)-catalyzed enantioselective transfer hydrogenation of ketones and fabrication of hybrid heterojunctions
Ak, Bünyamin,Aydemir, Murat,Ocak, Yusuf Selim,Durap, Feyyaz,Kayan, Cezmi,Baysal, Akin,Temel, Hamdi
, p. 244 - 253 (2013/12/04)
A variety of phosphinite based on ferrocenyl moiety possessing central chirality have been screened as ligands for ruthenium(II)-catalyzed transfer hydrogenation of acetophenone derivatives using iso-PrOH as the hydrogen source to afford the corresponding product, (R) or (S)-1-phenylethanol derivatives with high conversions and good enantioselectivities. These complexes were also employed in the asymmetric reduction of different prochiral ketones (up to 85% ee). A comparison of the catalytic properties of amino alcohols and other analogs based on ferrocenyl backbone is also discussed briefly. The structures of these ligands and their corresponding complexes have been elucidated by a combination of multinuclear NMR spectroscopy, IR spectroscopy and elemental analysis. Furthermore, organic-inorganic hybrid heterojunctions were also fabricated by forming thin films of ruthenium(II) complexes on n-Si and evaporation of Au as front contact. Current-voltage (I-V) characteristics of the structures showed excellent rectification properties. Electrical parameters including ideality factor, barrier height and series resistance were determined using I-V and capacitance-voltage (C-V) data. Finally, photoelectrical properties of the structures were examined by means of a solar simulator with AM1.5 global filter.
Highly enantioselective Michael addition of diethyl malonate to chalcones catalyzed by cinchona alkaloids-derivatived bifunctional tertiary amine-thioureas bearing multiple hydrogen-bonding donors
Liu, Yulong,Wang, Xie,Wang, Xiaoyun,He, Wei
supporting information, p. 3163 - 3166 (2014/05/06)
Chalcones are still challenge substrates in Michael reactions, and only limited success has been achieved. This work describes a highly enantioselective Michael addition of diethyl malonate with chalcones catalyzed by cinchona alkaloids-derivatived bifunctional tertiary amine-thioureas bearing multiple hydrogen-bonding donors.
Synthesis of salicylic acid-based 1,3,4-oxadiazole derivatives coupled with chiral oxazolidinones: Novel hybrid heterocycles as antitumor agents
Murty,Penthala, Raju,Nath, Lekshmi R.,Anto, Ruby John
, p. 1133 - 1142 (2015/03/31)
A series of novel salicylic acid-based 1,3,4-oxadiazoles derivatives coupled with chiral oxazolidinones were synthesized to screen for their in vitro antitumor activity against five human cancer cell lines. Some of these compounds showed good antitumor activities with IC50values ranging from 31.19-57.21 μM. Among the tested compounds 11, 15, 19,23,24, and 34 showed broad-spectrum antitumor activity against all the cell lines. In particular, compound 19 revealed remarkable antitumor activity with IC50 = 31.19-41.87 μM. A431 was the most sensitive cell line against all the compounds studied, followed by HeLa, MCF-7, A549 and HepG2. Structures of newly synthesized compounds were confirmed by IR,1 H NMR, 13C NMR and HRMS spectral data
Tunable ferrocenyl-phosphinite ligands for the ruthenium(II)-catalyzed asymmetric transfer hydrogenation of ketones
I?ik, U?ur,Aydemir, Murat,Meri?, Nermin,Durap, Feyyaz,Kayan, Cezmi,Temel, Hamdi,Baysal, Akin
, p. 225 - 233 (2013/10/08)
We report here new examples of enantiomerically pure monodendate phosphinite ligands containing both a ferrocene moiety and NH bridging moiety adjacent to the stereocenter, as well as their ruthenium(II) dichloro complexes. The phosphinites based on ferrocenyl moiety possessing stereogenic center have been screened as ligands for ruthenium(II)-catalyzed transfer hydrogenation of aromatic ketones to give corresponding secondary alcohols using iso-PrOH as the hydrogen source in the presence of NaOH. Up to 99% conversion with 97% ee was obtained in the transfer hydrogenation of acetophenone derivatives. Furthermore, the catalytic properties of these catalysts based on ferrocenyl-phosphinite backbone are also discussed briefly. The structures of these ligand and their corresponding complexes have been elucidated by a combination of multinuclear NMR spectroscopy, IR spectroscopy and elemental analysis.
