Protecting-Group-Free Total Synthesis of (−)-Jiadifenolide: Development of a [4 + 1] Annulation toward Multisubstituted Tetrahydrofurans

2015 ◽  
Vol 17 (21) ◽  
pp. 5480-5483 ◽  
Author(s):  
Yang Shen ◽  
Linbin Li ◽  
Zhisheng Pan ◽  
Yinglu Wang ◽  
Jundong Li ◽  
...  
Keyword(s):  
Total Synthesis ◽  
Protecting Group

Short Protecting Group-free Syntheses of CDE Synthon of Racemic Camptothecin

2020 ◽  
Vol 17 (7) ◽  
pp. 588-591
Author(s):  
Pingxuan Shao ◽  
Wei Lu ◽  
Lei Wang
Keyword(s):  
Total Synthesis ◽  
Future Development ◽  
Protecting Group ◽  
Short Route ◽  
The Future ◽  
Tricyclic Ketone

A practical and concise total synthesis of tricyclic ketone 7 (CDE ring), a valuable intermediate for the synthesis of racemic camptothecin and analogs, was described (8 chemical steps and 29% overall yield). The synthesis starts with two inexpensive, readily available materials and is operationally simple to perform. It is worth mentioning that the reported protecting group-free synthesis, with advantages of a short route, would be helpful for the future development of industry-scale syntheses of camptothecin-family alkaloids.

scholarly journals Revision of the Structure and Total Synthesis of Topsentin C

Synthesis ◽  
2017 ◽  
Vol 49 (11) ◽  
pp. 2562-2574 ◽  
Author(s):  
Nikita Golantsov ◽  
Alexey Festa ◽  
Alexey Varlamov ◽  
Leonid Voskressensky
Keyword(s):  
Total Synthesis ◽  
Secondary Metabolite ◽  
Conjugate Addition ◽  
Solvent Free ◽  
Synthetic Approach ◽  
Protecting Group ◽  
Marine Alkaloids ◽  
Mild Reduction

An efficient synthetic approach to access (indol-3-yl)ethane-1,2-diamines with a protecting group at the indole N atom from readily available 3-(2-nitrovinyl)indoles is reported. This approach includes solvent-free conjugate addition of O-pivaloylhydroxylamines to 1-Boc-3-(2-nitrovinyl)indoles followed by mild reduction of the adducts. The obtained (indol-3-yl)ethane-1,2-diamines are convenient synthetic precursors for several classes of marine alkaloids. The first total synthesis of racemic topsentin C, a secondary metabolite from Hexadella sp., based on this approach is reported. The initially proposed structure for topsentin C has been revised.

scholarly journals A Reliable Enantioselective Route to Mono-Protected N1-Cbz Piperazic Acid Building Block

Molecules ◽  
2020 ◽  
Vol 25 (24) ◽  
pp. 5939
Author(s):  
Evanthia Papadaki ◽  
Dimitris Georgiadis ◽  
Michail Tsakos
Keyword(s):  
Natural Products ◽  
Amino Acid ◽  
Total Synthesis ◽  
Building Block ◽  
Optical Purity ◽  
Protecting Group ◽  
High Optical Purity

The chiral N1-Cbz, N2-H derivative of the piperazic acid monomer is a valuable building block in the total synthesis of natural products, comprising this nonproteinogenic amino acid. In that context, we wish to report an improved synthetic protocol for the synthesis of both (3R)- and (3S)-piperazic acids bearing the carboxybenzyl protecting group (Cbz) selectively at the N1 position. Our method builds on previously reported protocols, circumventing their potential shortcomings, and optimizing the ultimate selective deprotection at the N2 position, thus, offering an efficient and reproducible pathway to suitably modified piperazates in high optical purity.

First total synthesis of WLIP: on the importance of correct protecting group choice

2016 ◽  
Vol 22 (3) ◽  
pp. 149-155 ◽  
Author(s):  
Matthias De Vleeschouwer ◽  
José C. Martins ◽  
Annemieke Madder
Keyword(s):  
Total Synthesis ◽  
Protecting Group ◽  
Group Choice

Total synthesis of (±)-9-deoxygoniopypyrone. Application of the iodocyclofunctionalization reaction of bold α-allenic alcohol derivatives

1998 ◽  
Vol 76 (1) ◽  
pp. 94-101 ◽  
Author(s):  
Richard W Friesen ◽  
Suzanne Bissada
Keyword(s):  
Total Synthesis ◽  
Primary Alcohol ◽  
Silyl Ether ◽  
Protecting Group ◽  
Acetylenic Ester ◽  
The Third ◽  
Vicinal Diol ◽  
Epoxide Opening ◽  
Vinyl Iodide ◽  
Acidic Conditions

The synthesis of ( ±)-9-deoxygoniopypyrone (1) from the α-allenic alcohol 5 is described. Iodocyclofunctionaliztion of the N-tosyl carbamate derivative of 5 using I2 and Ag2CO3 provided, in a highly diastereoselective and regioselective fashion, the vinyl iodo syn-vicinal diol 4. Two routes were explored in order to introduce the third stereogenic centre in the molecule. Reductive deiodination of the vinyl iodide and diastereoselective epoxidation of the derived acetonide14 using mCPBA provided a mixture of epoxides 15 and 16 (2:1) in which the desired threo diastereomer predominated. Alternatively, dihydroxylation of acetonide 14 (OsO4, NMO) yielded a mixture of diols 21 and 22 (2:3) which were separated after monosilylation (TBDMSCl) of the primary alcohol. The major silyl ether erythro diastereomer 24 was converted to the desired epoxide 15 by mesylation (MsCl, Et3N) and epoxide formation (TBAF) with inversion of stereochemistry. The minor threo diastereomer 23 was also converted to the desired epoxide 15 (TBAF; ArSO2Cl; NaOMe). Epoxide opening was effected with lithium acetylide and the resulting alkyne 27 was carbonylated (MeLi, ClCO2Me) to afford the α , β-acetylenic ester 28. Semi hydrogenation over Lindlar's catalyst followed by protecting- group removal under acidic conditions provided ( ±)-8-epigoniodiol 30. Finally, conversion of 30 to ( ±)-9-deoxygoniopypyrone 1 was effected under basic conditions (DBU).Key words: ( ±)-9-deoxygoniopypyrone, α-allenic alcohol, iodocyclofunctionalization, syn-diol.

Total synthesis of polyamine toxin HO-416b utilizing the 2-nitrobenzenesulfonamide protecting group

1999 ◽  
Vol 40 (25) ◽  
pp. 4711-4714 ◽  
Author(s):  
Yuko Hidai ◽  
Toshiyuki Kan ◽  
Tohru Fukuyama
Keyword(s):  
Total Synthesis ◽  
Protecting Group

scholarly journals Synthetic and semi-synthetic approaches to unprotected N-glycan oxazolines

2018 ◽  
Vol 14 ◽  
pp. 416-429 ◽  
Author(s):  
Antony J Fairbanks
Keyword(s):  
Total Synthesis ◽  
Important Application ◽  
Protecting Group ◽  
Natural Sources ◽  
Bean Flour ◽  
Egg Yolks ◽  
Synthetic Sequence ◽  
The Many ◽  
Synthetic Approaches ◽  
Selection Of

N-Glycan oxazolines have found widespread use as activated donor substrates for endo-β-N-acetylglucosaminidase (ENGase) enzymes, an important application that has correspondingly stimulated interest in their production, both by total synthesis and by semi-synthesis using oligosaccharides isolated from natural sources. Amongst the many synthetic approaches reported, the majority rely on the fabrication (either by total synthesis, or semi-synthesis from locust bean gum) of a key Manβ(1–4)GlcNAc disaccharide, which can then be elaborated at the 3- and 6-positions of the mannose unit using standard glycosylation chemistry. Early approaches subsequently relied on the Lewis acid catalysed conversion of peracetylated N-glycan oligosaccharides produced in this manner into their corresponding oxazolines, followed by global deprotection. However, a key breakthrough in the field has been the development by Shoda of 2-chloro-1,3-dimethylimidazolinium chloride (DMC), and related reagents, which can direct convert an oligosaccharide with a 2-acetamido sugar at the reducing terminus directly into the corresponding oxazoline in water. Therefore, oxazoline formation can now be achieved in water as the final step of any synthetic sequence, obviating the need for any further protecting group manipulations, and simplifying synthetic strategies. As an alternative to total synthesis, significant quantities of several structurally complicated N-glycans can be isolated from natural sources, such as egg yolks and soy bean flour. Enzymatic transformations of these materials, in concert with DMC-mediated oxazoline formation as a final step, allow access to a selection of N-glycan oxazoline structures both in larger quantities and in a more expedient fashion than is achievable by total synthesis.

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