scholarly journals A stereoselective and flexible synthesis to access both enantiomers of N-acetylgalactosamine and peracetylated N-acetylidosamine

2018 ◽  
Vol 14 ◽  
pp. 856-860 ◽  
Author(s):  
Bettina Riedl ◽  
Walther Schmid
Keyword(s):  
Cell Signaling ◽  
Nucleophilic Substitution ◽  
Tartaric Acid ◽  
Cell Interaction ◽  
Synthetic Route ◽  
Target Compound ◽  
Stereogenic Centers ◽  
Epoxide Opening ◽  
Epoxy Alcohols ◽  
Synthetic Approaches

Synthetic approaches towards N-acetylgalactosamine (GalNAc) have been attracting considerable interest since this compound is known for its pivotal role in cell–cell interaction and receptor induced cell signaling. Herein, we present a synthetic route in which two of the four stereogenic centers present in the target compound are derived from enantiopure tartaric acid being selectively converted to epoxy alcohols. The key step is the Pd-catalyzed, stereo- and regioselective epoxide opening and subsequent nucleophilic substitution of an azide functionality. This approach enables the synthesis of the naturally D- and unnaturally L-configured GalNAc, as well as both enantiomers of the largely unknown N-acetylidosamine (IdoNAc).

Chemical Diversity of Volatile Macrocylic Lactones from Frogs

Synlett ◽  
2021 ◽  
Author(s):  
Stefan Schulz ◽  
Dennis Poth ◽  
Pardha Saradhi Peram ◽  
Susann Hötling ◽  
Markus Menke ◽  
...  
Keyword(s):  
Biosynthetic Pathway ◽  
Chemical Diversity ◽  
Synthetic Methods ◽  
Epoxide Opening ◽  
Scientific Approach ◽  
Long Time ◽  
Fatty Acid Biosynthetic Pathway ◽  
Unsaturated Lactones ◽  
Male Specific ◽  
Synthetic Approaches

AbstractFor a long time, frogs were believed to communicate primarily via the acoustic channel, but during the last decades it became obvious that various lineages also use chemical communication. In this Account we present our research on the identification of volatile lactones from Madagascan Mantellidae and African Hyperoliidae frogs. Both possess male specific glands that can disseminate a range of volatile compounds. Key constituents are macrocyclic lactones. They show high variability in structure and occurrence. We focus here on the synthetic approaches we have used to clarify constitution and configuration of the glandular compounds. Key synthetic methods are ring-closing metathesis and nucleophilic epoxide opening. Often, but not always, the natural compounds occurs in amounts that excludes their investigation by NMR spectroscopy. Instead, we use GC/MS analysis, GC/IR, microreactions, and synthesis to identify such components. Several aspects of our work will be described giving some insight in our scientific approach.1 Introduction2 Macrocylic Lactones from the Fatty Acid Biosynthetic Pathway3 Unsaturated Lactones4 Terpenoid Lactones5 Macrolide Occurrence6 Conclusions

Stereodivergent Access to Enantioenriched Epoxy Alcohols with Three Stereogenic Centers via Ruthenium-Catalyzed Transfer Hydrogenation

2019 ◽  
Vol 21 (14) ◽  
pp. 5491-5494 ◽  
Author(s):  
Zhifei Zhao ◽  
Prasanta Ray Bagdi ◽  
Shuang Yang ◽  
Jinggong Liu ◽  
Weici Xu ◽  
...  
Keyword(s):  
Transfer Hydrogenation ◽  
Stereogenic Centers ◽  
Epoxy Alcohols

Synthetic Approaches to Optically Active Macrolides Containing Hydrazide Fragments of L-(+)-Tartaric Acid from (+)-3-Carene, (+)-α-Pinene, and S-(–)-Limonene

2014 ◽  
Vol 50 (4) ◽  
pp. 658-660 ◽  
Author(s):  
G. Yu. Ishmuratov ◽  
M. P. Yakovleva ◽  
M. A. Shutova ◽  
R. R. Muslukhov ◽  
N. M. Ishmuratova ◽  
...  
Keyword(s):  
Tartaric Acid ◽  
Optically Active ◽  
Synthetic Approaches

The Nicolaou Synthesis of (+)-Hirsutellone B

2013 ◽  
Author(s):  
Douglass F. Taber
Keyword(s):  
Mycobacterium Tuberculosis ◽  
Pathogenic Fungus ◽  
Catalytic Amount ◽  
Diels Alder ◽  
Good Activity ◽  
Stereogenic Centers ◽  
Epoxide Opening ◽  
Carbocyclic Rings ◽  
La Jolla ◽  
Stereogenic Center

(+)-Hirsutellone B 3, isolated from the insect pathogenic fungus Hirsutella nivea BCC 2594, shows good activity (MIC = 0.78 μg/mL) against Mycobacterium tuberculosis. Approaching the synthesis of 3, K. C. Nicolaou of Scripps/La Jolla envisioned and reduced to practice (Angew. Chem. Int. Ed. 2009, 49, 6870) a spectacular tandem intramolecular epoxide opening: internal Diels-Alder cyclization (1 2) that established all three of the carbocyclic rings of 3 with the proper relative and absolute configuration. The construction of 1 began with commercial ( R) -(+)-citronellal 4. Wittig homologation established the ( Z )-iodide 5. Selective ozonolysis followed by condensation with the phosphorane 7 set the stage for Jørgensen-Córdova (Tetrahedron Lett. 2006, 47, 99) epoxidation with H2O2 and a catalytic amount of the Hayashi catalyst 9. Condensation of 10 with the phosphorane 11 followed by Cu-catalyzed coupling of 12 with the organostannane 13 completed the assembly of 1. This approach underscores the strategic advantages of the Jørgensen-Córdova epoxidation over the Sharpless protocol. It is not necessary to reduce the aldehyde to the allyic alcohol, then reoxidize. Furthermore, the Jørgensen-Córdova epoxidation, using catalytic 9, is operationally easier than the Sharpless procedure, which often uses stoichiometric amounts of tartrate ester. The cyclization of 1 proceeded by way of 13, with the newly formed stereogenic center having the diene equatorial on the cyclohexane. Endo cycloaddition catalyzed by the Lewis acid in the solution then gave 2. The facility with which the cyclization of 13 set both the substituents and the stereogenic centers of 2 raises the possibility that the biosynthesis might also follow such an internal [4 + 2] cycloaddition. To complete the synthesis of 3, it was necessary to construct the strained paracyclophane. The authors took advantage of the facile cyclization of the thiolate liberated from 18, then installed the ring-contracted alkene with a Ramburg-Bäcklund rearrangement of 19. They completed the synthesis of (+)-hirsutellone B 3 by exposing the ketone 21 to NH3 in CH3OH/H2O.

scholarly journals An improved process for the preparation of pimavanserin tartrate

2019 ◽  
Vol 43 (11-12) ◽  
pp. 480-485
Author(s):  
Caijiao Wu ◽  
Qifan Zhou ◽  
Dake Song ◽  
Hui Li ◽  
Changshun Bao ◽  
...  
Keyword(s):  
Total Yield ◽  
Synthetic Route ◽  
Target Compound ◽  
Reaction Conditions

A practical synthetic route to pimavanserin tartrate, in which the target compound was obtained with 99.84% purity and in 46% total yield via a 5-step synthesis starting from 4-hydroxybenzaldehyde and (4-fluorophenyl)methanamine, is reported. The main advantages of the route include inexpensive starting materials, mild reaction conditions and an acceptable overall yield.

scholarly journals An Improved Synthetic Route to the Potent Angiogenesis Inhibitor Benzyl Manα(1→3)-Manα(1→3)-Manα(1→3)-Manα(1→2)-Man Hexadecasulfate

2009 ◽  
Vol 62 (6) ◽  
pp. 546 ◽  
Author(s):  
Ligong Liu ◽  
Ken D. Johnstone ◽  
Jon K. Fairweather ◽  
Keith Dredge ◽  
Vito Ferro
Keyword(s):  
Building Block ◽  
Angiogenesis Inhibitor ◽  
Building Blocks ◽  
Synthetic Route ◽  
Target Compound ◽  
Angiogenic Activity

An improved synthetic route to α(1→3)/α(1→2)-linked mannooligosaccharides has been developed and applied to a more efficient preparation of the potent anti-angiogenic sulfated pentasaccharide, benzyl Manα(1→3)-Manα(1→3)-Manα(1→3)-Manα(1→2)-Man hexadecasulfate, using only two monosaccharide building blocks. Of particular note are improvements in the preparation of both building blocks and a simpler, final deprotection strategy. The route also provides common intermediates for the introduction of aglycones other than benzyl, either at the building block stage or after oligosaccharide assembly. The anti-angiogenic activity of the synthesized target compound was confirmed via the rat aortic assay.

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