Efficient Synthesis of Bicyclic Peptide BI-32169 Utilizing a Novel Aryl Boronate Ester Protecting Group

2018 ◽  
Vol 76 (2) ◽  
pp. 95
Author(s):  
Hui Song ◽  
Chao Liu ◽  
Yijun Wu ◽  
Honggang Hu ◽  
Fang Yan
Keyword(s):  
Protecting Group ◽  
Efficient Synthesis ◽  
Boronate Ester

Protecting-Group-Directed Regio- and Stereoselective Oxymercuration–Demercuration: Synthesis of Piperidine Alkaloids Containing 1,2- and 1,3-Amino Alcohol Units

Synthesis ◽  
2017 ◽  
Vol 50 (05) ◽  
pp. 1113-1122 ◽  
Author(s):  
Santosh Tilve ◽  
Sandesh Bugde ◽  
Prajesh S.Volvoikar
Keyword(s):  
Amino Alcohol ◽  
Protecting Groups ◽  
Protecting Group ◽  
Efficient Synthesis ◽  
Piperidine Alkaloids ◽  
Naturally Occurring ◽  
Pipecolinic Acid

An efficient synthesis of naturally occurring 1,2- and 1,3-amino alcohol unit containing 2-substituted piperidine alkaloids and their analogues has been developed from l-pipecolinic acid. The protocol describes the regio- and stereoselective oxymercuration–demercuration of 2-alkenyl piperidines based on protecting groups to give piperidine alkaloids as a key step.

scholarly journals Methodology development for the synthesis of iminosugars

2021 ◽  
Author(s):  
◽  
Alexander Hunt-Painter
Keyword(s):  
Reductive Amination ◽  
Steric Effects ◽  
Primary Amines ◽  
Equatorial Position ◽  
Protecting Group ◽  
Efficient Synthesis ◽  
Electronic Effects ◽  
Synthetic Methodology ◽  
Methodology Development ◽  
The One

<p>This thesis investigated the development and application of methodology for the synthesis of iminosugars. The first portion of this thesis (Chapters 2 and 3) explored the scope of previously established protecting-group-free Vasella-reductive-amination and I2-mediated carbamate annulation methodology initially developed within the Stocker-Timmer group for the synthesis of pyrrolidines and piperidines from aldose sugars. In this thesis, the Vasella-reductive-amination methodology was extended to include the use of ketose sugars as starting materials, thereby allowing for the synthesis of primary amines directly from in situ formed ketones under protecting-group-free conditions. The scope of the carbamate annulation was then explored, whereby it was determined that both steric and electronic effects appear to affect transition state energies during the annulation reaction. Here, formation of pyrrolidines with the 2,5-trans and 3,4-cis relationships are favoured, however, in circumstances were conflicting electronic- and steric-effects are present, steric-effects dominate thereby favouring the formation of the 2,5-trans product. Using a combination of this Vasella-reductive-amination and carbamate annulation methodology, 2,5-dideoxy-2,5-imino-L-iditol was thus synthesised in 6 steps and 18% overall yield from D-fructose. Next, the same methodology was applied to the synthesis of the promising molecular chaperone 2,5-dideoxy-2,5-imino-D-altritol. Thus, 2,5-dideoxy-2,5-imino-D-altritol was synthesised over 7 steps and in 22% yield from D-tagatose, which is the most efficient synthesis of this iminosugar to date.  The second part of this thesis (Chapters 4 and 5) focused on the optimisation and development of synthetic methodology that would allow for the highly efficient synthesis of a variety of iminosugars including piperidines and azepanes. To this end, modifications to existing synthetic methodology allowed for the rapid synthesis of a variety of iodoglycosides, which are important synthons. Next, reductive amination/cyclisation methodology that allowed for the direct transformation of methyl iodoglycosides or isopropylidene-protected iodoglycosides into iminosugars was developed. As such, the piperidines 1-Deoxynojirimycin, 1-Deoxymannojirimycin (DMJ), L-1-Deoxygalactojirimycin (L-DGJ), and (3R,4r,5S)-piperidine-3,4,5-triol were prepared in 4 steps and good overall yields (44%, 62%, 67%, and 53%, respectively). In the case of DMJ and (3R,4r,5S)-piperidine-3,4,5-triol, these are the most efficient syntheses of these materials to date. Factors influencing the stereochemical outcome of the reductive amination reaction were also explored, and evidence suggests that the reduction occurs from the least sterically hindered face of an intermediate cyclic imine, whereby the preferred conformation of the imine is the one which places the largest number of substituents in the pseudo-equatorial position. Using analogous methodology, the azepane (3S,4R,5S,6R)-azepane-3,4,5,6-tetraol was also prepared in 4 steps and good yield (53%).</p>

scholarly journals An Efficient Synthesis of Tetrodotoxin

2021 ◽  
Author(s):  
David Konrad ◽  
Peter Ruehmann ◽  
Hiroyasu Ando ◽  
Belinda Hetzler ◽  
Bryan Matsuura ◽  
...  
Keyword(s):  
Tertiary Amine ◽  
Stereoselective Synthesis ◽  
Primary Alcohol ◽  
Biologically Active ◽  
Dipolar Cycloaddition ◽  
Protecting Group ◽  
Efficient Synthesis ◽  
Ready Access ◽  
Biologically Active Derivatives ◽  
Glucose Derivative

Tetrodotoxin (TTX) is an indispensable probe in neuroscience, a biosynthetic and ecological enigma, and one of the most celebrated targets of synthetic chemistry. Here, we present a stereoselective synthesis of TTX that proceeds in 22 steps starting from a readily available glucose derivative. The central cyclohexane ring of TTX and its α-tertiary amine moiety was established via the intramolecular 1,3-dipolar cycloaddition of a nitrile oxide, followed by alkynyl addition to the resultant isoxazoline. After some carefully chosen protecting group manipulations, a ruthenium-catalyzed hydroxylactonization set the stage for the formation of its dioxa-adamantane core. Installation of the guanidine, oxidation of a primary alcohol, and late-stage epimerization of the resultant aldehyde gave a mixture of TTX and anhydro TTX. Our synthesis represents one of the most effective of TTX reported to date and could give ready access to biologically active derivatives.

Application of the PMC Protecting Group in the Efficient Synthesis of 4,4‐Disubstituted Piperidines

2005 ◽  
Vol 35 (12) ◽  
pp. 1613-1625 ◽  
Author(s):  
Janet L. Ralbovsky ◽  
Joseph G. Lisko ◽  
Wei He
Keyword(s):  
Protecting Group ◽  
Efficient Synthesis

ChemInform Abstract: Protecting Group Free Synthesis of Urea-Linked Glycoconjugates: Efficient Synthesis of β-Urea Glycosides in Aqueous Solution.

ChemInform ◽  
2014 ◽  
Vol 45 (45) ◽  
pp. no-no
Author(s):  
Yoshiyasu Ichikawa ◽  
Takahiro Minami ◽  
Shohei Kusaba ◽  
Nobuyoshi Saeki ◽  
Yuta Tonegawa ◽  
...  
Keyword(s):  
Aqueous Solution ◽  
Protecting Group ◽  
Efficient Synthesis

Application of the PMC Protecting Group in the Efficient Synthesis of 4,4-Disubstituted Piperidines.

ChemInform ◽  
2005 ◽  
Vol 36 (47) ◽  
Author(s):  
Janet L. Ralbovsky ◽  
Joseph G. Lisko ◽  
Wei He
Keyword(s):  
Protecting Group ◽  
Efficient Synthesis

scholarly journals Synthesis of Plakortolides E and I Enabled by Base Metal Catalysis

2021 ◽  
Author(s):  
Stefan Leisering ◽  
Alexandros Mavroskoufis ◽  
Patrick Voßnacker ◽  
Reinhold Zimmer ◽  
Mathias Christmann
Keyword(s):  
Natural Products ◽  
Transition Metals ◽  
Base Metal ◽  
Protecting Group ◽  
Efficient Synthesis ◽  
One Pot ◽  
Metal Catalysis ◽  
Bond Forming ◽  
Earth Abundant ◽  
Key Steps

A protecting-group-free synthesis of two endoperoxide natural products, plakortolide E and plakortolide I, is reported. Key-steps feature the use of earth-abundant transition metals, consisting of a vanadium-mediated epoxidation, an iron-catalyzed allylic substitution, and a cobalt-induced endoperoxide formation. Our approach combines redox-economy, chemoselective bond-forming reactions, and telescoping into one-pot operations to forge an overall efficient synthesis.

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