Asymmetric formal synthesis of (+)-cycloclavine

2017 ◽  
Vol 53 (96) ◽  
pp. 12902-12905 ◽  
Author(s):  
Jin-Quan Chen ◽  
Le-Le Song ◽  
Feng-Xing Li ◽  
Zi-Fa Shi ◽  
Xiao-Ping Cao
Keyword(s):  
Asymmetric Synthesis ◽  
Direct Access ◽  
Formal Synthesis ◽  
First Time

The asymmetric synthesis of Szántay's amine (+)-2, the pivotal precursor for direct access to (+)-cycloclavine (1), is described for the first time in eleven steps with 19.7% overall yield from the commercially available 4-bromoindole.

scholarly journals Catalytic asymmetric formal synthesis of beraprost

2015 ◽  
Vol 11 ◽  
pp. 2654-2660 ◽  
Author(s):  
Yusuke Kobayashi ◽  
Ryuta Kuramoto ◽  
Yoshiji Takemoto
Keyword(s):  
Asymmetric Synthesis ◽  
Michael Reaction ◽  
Subsequent Reduction ◽  
Formal Synthesis ◽  
Michael Adduct ◽  
Catalytic Asymmetric Synthesis ◽  
Weinreb Amide ◽  
Tricyclic Core ◽  
Catalytic Asymmetric

The first catalytic asymmetric synthesis of the key intermediate for beraprost has been achieved through an enantioselective intramolecular oxa-Michael reaction of an α,β-unsaturated amide mediated by a newly developed benzothiadiazine catalyst. The Weinreb amide moiety and bromo substituent of the Michael adduct were utilized for the C–C bond formations to construct the scaffold. All four contiguous stereocenters of the tricyclic core were controlled via Rh-catalyzed stereoselective C–H insertion and the subsequent reduction from the convex face.

Nickel-catalysed alkylation of C(sp3)–H bonds with alcohols: direct access to functionalised N-heteroaromatics

2018 ◽  
Vol 54 (87) ◽  
pp. 12369-12372 ◽  
Author(s):  
Mari Vellakkaran ◽  
Jagadish Das ◽  
Sourajit Bera ◽  
Debasis Banerjee
Keyword(s):  
Base Metal ◽  
Direct Access ◽  
First Time

Base-metal catalysed C(sp3)–H bond functionalisation of methyl-N-heteroaromatics with alcohols is reported for the first time.

scholarly journals Visualization of the Ludford column

2013 ◽  
Vol 721 ◽  
pp. 438-453 ◽  
Author(s):  
Oleg Andreev ◽  
Yurii Kolesnikov ◽  
André Thess
Keyword(s):  
Liquid Metals ◽  
Basic Feature ◽  
Direct Access ◽  
Experimental Procedure ◽  
Stagnant Region ◽  
Tracer Particles ◽  
Image Velocimetry ◽  
Truncated Cylinder ◽  
First Time ◽  
Flow Experiments

AbstractWhen a liquid metal flows around a truncated cylinder in the presence of a magnetic field which is parallel to the axis of the cylinder, a stagnant region develops above the cylinder. We call this region a Ludford column. The Ludford column represents the magnetohydrodynamics (MHD) analogue of the well-known Taylor columns in rotating flows. Whereas Taylor columns can be easily visualized using dye, the visualization of Ludford columns has remained elusive up to now because liquid metals are opaque. We demonstrate that this fundamental limitation of experimental MHD can be overcome by using a superconducting 5 T magnet. This facility permits us to perform MHD experiments in which the opaque liquid metals are replaced with a transparent electrolyte while maintaining the key MHD effects. We report results of a series of flow experiments in which an aqueous solution of sulphuric acid flows around a bar with square cross-section (which for simplicity shall be referred to as a cylinder). We vary the Reynolds number in the range $5\lt Re\lt 100$ and the Hartmann number in the range $0\lt Ha\lt 14$. The experimental procedure involves flow visualizations using tracer particles as well as velocity measurements using particle image velocimetry (PIV). Our experiments provide direct access to the Ludford column for the first time and reveal the spatial structure of this basic feature of MHD flows.

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