Total Synthesis of Complex Cyanobacterial Alkaloids without Using Protecting Groups

2007 ◽  
Vol 46 (30) ◽  
pp. 5656-5658 ◽  
Author(s):  
Karl Gademann ◽  
Simone Bonazzi
Keyword(s):  
Total Synthesis ◽  
Protecting Groups

Zur Totalsynthese des Human-Big-Gastrins I und seines 32-Leucin-Analogons (Vorläufige Mitteilung) / Total Synthesis of Human Big Gastrin I and the 32-Leucine Analogue (Preliminary Communication)

1977 ◽  
Vol 32 (7-8) ◽  
pp. 495-506 ◽  
Author(s):  
E. Wünsch ◽  
G. Wendlberger ◽  
A. Hallett ◽  
E. Jaeger ◽  
S. Knof ◽  
...  
Keyword(s):  
Total Synthesis ◽  
Building Blocks ◽  
Ion Exchange Chromatography ◽  
Exchange Chromatography ◽  
Protecting Groups ◽  
Side Chain ◽  
Tertiary Alcohols ◽  
Synthetic Product ◽  
Preliminary Communication ◽  
Final Purification

A new total synthesis of the tetratriacontapeptide amide corresponding to the proposed primary structure of human big gastrin I is described. The synthetic route was based on the preparation of six suitably protected fragments, related to sequence 28 - 34, 23 - 27, 21 - 22, 15-20, 9 - 14, and 1 - 8, to be used as building blocks for the total synthesis. The protecting groups were selected according to the Schwyzer-Wünsch strategy of maximum side chain protection based on tertiary alcohols, also for the imidazol function of histidine. Subsequent assembly of the six fragments by three different pathways using the highly efficient Wünsch-Weygand condensation procedure to ensure minimum racemization, followed by deprotection of the synthetic products via exposure to trifluoroacetic acid and final purification by ion-exchange chromatography on DEAE-Sephadex A-25 and partition chromatography on Sephadex G-25, led to human big gastrin I, homogeneous within the limits of the analytical methods used. The biological activity of the synthetic product proved to be 50 percent higher than that of human little gastrin I. The 32-leucine analogue of human big gastrin I was prepared in the same way.

scholarly journals Total synthesis of TMG-chitotriomycin based on an automated electrochemical assembly of a disaccharide building block

2017 ◽  
Vol 13 ◽  
pp. 919-924 ◽  
Author(s):  
Yuta Isoda ◽  
Norihiko Sasaki ◽  
Kei Kitamura ◽  
Shuji Takahashi ◽  
Sujit Manmode ◽  
...  
Keyword(s):  
Total Synthesis ◽  
Building Block ◽  
Building Blocks ◽  
Solution Phase ◽  
Protecting Groups ◽  
Phase Synthesis ◽  
Solution Phase Synthesis

The total synthesis of TMG-chitotriomycin using an automated electrochemical synthesizer for the assembly of carbohydrate building blocks is demonstrated. We have successfully prepared a precursor of TMG-chitotriomycin, which is a structurally-pure tetrasaccharide with typical protecting groups, through the methodology of automated electrochemical solution-phase synthesis developed by us. The synthesis of structurally well-defined TMG-chitotriomycin has been accomplished in 10-steps from a disaccharide building block.

Synthesis of Optically Active 15-epi-9,14-Methylene Lipoxin A4

Synthesis ◽  
2018 ◽  
Vol 50 (06) ◽  
pp. 1246-1258
Author(s):  
Udo Nubbemeyer ◽  
Adile Duymaz ◽  
Jochen Körber ◽  
Carolin Hofmann ◽  
Dorothea Gerlach
Keyword(s):  
Total Synthesis ◽  
Building Block ◽  
Building Blocks ◽  
Optically Active ◽  
Protecting Groups ◽  
Lipoxin A4 ◽  
Methylene Bridge ◽  
Type Coupling ◽  
Important Field ◽  
Gain Access

The synthesis of lipoxin A4 and B4 analogues (LXA4, LXB4) to gain access to stabilized inflammation resolving compounds is an important field of research. Starting from known structural requirements of the natural compounds displaying biological activity and a broad investigation of their rapid metabolism, various LXA4 derivatives have been developed and tested. Focusing on variation and stabilization of the conjugated E,E,Z,E C7–C14 tetraene moiety of natural LXA4, a methylene bridge introduced between C9 and C14 might suppress any Z/E isomerization of the C11–C12 olefin. Intending to enable at least known structure variations in connection with the C1–C7 and the C15–C20 fragments, a convergent total synthesis starting from a known cycloheptatriene is developed. The C1–C8 building blocks are generated via six-step ex-chiral pool sequences starting from 2-deoxy-d-ribose delivering two 5,6-dihydroxy carboxylic acid derivatives with C7 aldehyde functions. The synthesis of the C8–C21 building block starts from a known cycloheptatriene 1-carbonester (C8–C14, C21) and hexanoyl chloride (C15–C20). After Friedel–Crafts-type coupling, the defined configuration of the C15 OH group is introduced via enantioselective reduction of the ketone precursor. Following an additional four steps, an aryl sulfone C9–C21 building block is completed ready for a key Julia–Kocienski olefination with the C1–C7 compounds. Finally, removal of the protecting groups completes the synthesis of the target optically active 9,14-methylene LXA4 methyl ester.

Synthesis of the Reported Structure of Pogostol and a Total Synthesis of (±)-Kessane without the Use of Protecting Groups

2003 ◽  
Vol 5 (18) ◽  
pp. 3309-3312 ◽  
Author(s):  
Kevin I. Booker-Milburn ◽  
Helen Jenkins ◽  
Jonathan P. H. Charmant ◽  
Peter Mohr
Keyword(s):  
Total Synthesis ◽  
Protecting Groups

Protecting-Group-Free Total Synthesis of Anticancer (±)-Melotenine A

Synthesis ◽  
2021 ◽  
Author(s):  
Adisak Thanetchaiyakup ◽  
Hassayaporn Rattanarat ◽  
Sudaporn Aree ◽  
Tanwawan Duangthongyou ◽  
Tanin Nanok ◽  
...  
Keyword(s):  
Total Synthesis ◽  
Human Cancer ◽  
Alder Reaction ◽  
Diels Alder ◽  
Protecting Groups ◽  
Protecting Group ◽  
Ring Closing Metathesis ◽  
Human Cancer Cell Lines ◽  
Diels Alder Reaction ◽  
Key Steps

Melotenine A, isolated from Melodinus tenuicaudatus, possesses significant anticancer activity against several human cancer cell lines. The synthesis of (±)-melotenine A was achieved without the use of any protecting groups in 11 steps with an overall yield of 7%. The key steps of our strategy were the Diels–Alder reaction to construct the tetracyclic framework and ring-closing metathesis to form the seven-membered ring of (±)-melotenine A.

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