Synthesis of the core ring system of the stemona alkaloids by cascade condensation, cyclization, intramolecular cycloaddition

2010 ◽  
Vol 8 (20) ◽  
pp. 4530 ◽  
Author(s):  
Adam. J. M. Burrell ◽  
Luke Watson ◽  
Nathaniel G. Martin ◽  
Niall Oram ◽  
Iain Coldham
Keyword(s):  
Ring System ◽  
Intramolecular Cycloaddition ◽  
The Core ◽  
Stemona Alkaloids

Tele-Substitution Reactions in the Synthesis of a Promising Class of Antimalarials

2020 ◽  
Author(s):  
Marat Korsik ◽  
Edwin Tse ◽  
David Smith ◽  
William Lewis ◽  
Peter J. Rutledge ◽  
...  
Keyword(s):  
Heterocyclic Ring ◽  
Ring System ◽  
Substitution Reactions ◽  
Laboratory Notebook ◽  
Polar Solvents ◽  
X Ray ◽  
X Ray Crystallography ◽  
The Core ◽  
Nmr Data

<p></p><p>We have discovered and studied a <i>tele</i>substitution reaction in a biologically important heterocyclic ring system. Conditions that favour the <i>tele</i>-substitution pathway were identified: the use of increased equivalents of the nucleophile or decreased equivalents of base, or the use of softer nucleophiles, less polar solvents and larger halogens on the electrophile. Using results from X-ray crystallography and isotope labelling experiments a mechanism for this unusual transformation is proposed. We focused on this triazolopyrazine as it is the core structure of the <i>in vivo </i>active anti-plasmodium compounds of Series 4 of the Open Source Malaria consortium.</p> <p> </p> <p>Archive of the electronic laboratory notebook with the description of all conducted experiments and raw NMR data could be accessed via following link <a href="https://ses.library.usyd.edu.au/handle/2123/21890">https://ses.library.usyd.edu.au/handle/2123/21890</a> . For navigation between entries of laboratory notebook please use file "Strings for compounds in the article.pdf" that works as a reference between article codes and notebook codes, also this file contain SMILES for these compounds. </p><br><p></p>

An attempt to construct the C/D ring system of parkacine by intramolecular cycloaddition of azomethine ylide and alkyne

2016 ◽  
Vol 57 (18) ◽  
pp. 1981-1984 ◽  
Author(s):  
Wenxuan Zhang ◽  
Jiming Wang ◽  
Xihuan Luo ◽  
Xiangbao Meng ◽  
Zhongjun Li
Keyword(s):  
Ring System ◽  
Azomethine Ylide ◽  
Intramolecular Cycloaddition

N,N-Dialkyl-N'-Chlorosulfonyl Chloroformamidines in Heterocyclic Synthesis. Part VIII. Novel Pyrazolo-Fused Oxathiadiazines and Thiatriazoles

2010 ◽  
Vol 63 (4) ◽  
pp. 659 ◽  
Author(s):  
Craig M. Forsyth ◽  
Craig L. Francis ◽  
Saba Jahangiri ◽  
Andris J. Liepa ◽  
Michael V. Perkins ◽  
...  
Keyword(s):  
Recent Work ◽  
Major Product ◽  
Ring System ◽  
Heterocyclic Synthesis ◽  
Ring Systems ◽  
The Core ◽  
Derivatives Of

N,N-dialkyl-N′-chlorosulfonyl chloroformamidines 1 reacted with pyrazol-3-ones 2 under a variety of conditions to give pyrazolo[2,3-e][1,2,3,5]oxathiadiazine dioxides 3 and pyrazolo[3,2-b][1,4,3,5]oxathiadiazine dioxides 5, and frequently, one or both of pyrazolo[1,2-b][1,2,3,5]thiatriazole 1,1,5-trioxides 4 and 1,1,7-trioxides 6. In all reactions, the pyrazolo[3,2-b][1,4,3,5]oxathiadiazine 5 was the major product, with the pyrazolo[2,3-e][1,2,3,5]oxathiadiazine 3 being a significant product in the absence of base. Prior to our recent work, the core ring systems of compounds 3 and 5 had not been reported and compounds 4 and 6 are new derivatives of a rare ring system.

Synthetic Studies on Saframycin Anibiotics: An Improved Synthesis of Tricyclic Lactam Intermediate and Construction of the Core Ring System of Saframycin A

Heterocycles ◽  
2015 ◽  
Vol 90 (1) ◽  
pp. 327 ◽  
Author(s):  
Naoki Saito ◽  
Shinya Kimura ◽  
Shintaro Kawai ◽  
Masayuki Azuma ◽  
Yu-ichi Koizumi ◽  
...  
Keyword(s):  
Ring System ◽  
The Core ◽  
Synthetic Studies

scholarly journals Studies on polynuclear furoquinones. Part 1: Synthesis of tri- and tetra-cyclic furoquinones simulating BCD/ABCD ring system of furoquinone diterpenoids

2009 ◽  
Vol 5 ◽  
Author(s):  
Faruk Hasan Shaik ◽  
Gandhi Kumar Kar
Keyword(s):  
Acid Derivative ◽  
Boronic Acid ◽  
Functional Group ◽  
Suzuki Coupling ◽  
Ring System ◽  
Core Nucleus ◽  
Tanshinone I ◽  
The Core ◽  
Acetic Ester ◽  
Naphthyl Acetate

Synthesis of phenanthro[1,2-b]furan-10,11-dione, the core nucleus present in Tanshinone-I is described in 8–10 steps starting from 2-bromo-3,4-dihydro-1-naphthaldehyde. The bromoaldehyde was converted to methyl 2-(2-bromo-1-naphthyl)acetate or 2-(2-bromo-1-naphthyl)acetonitrile following the protocol of functional group transformations. Subsequent Suzuki coupling of this ester/nitrile derivative with furan-2-boronic acid produced [2-(2-furyl)-1-naphthyl]acetic ester/nitrile which on hydrolysis furnished the corresponding acid derivative. Cyclization of the acid followed by oxidation of the phenol, with Fremy’s salt, produced the tetra-cyclic furoquinone, phenanthro[1,2-b]furan-10,11-dione. This method has also been extended for the synthesis of the tricyclic furoquinone, naphtho[1,2-b]furan-4,5-dione.

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