Archive for June, 2014

When a Spectator is not Just a Spectator in Iodonium Salts

Advances in hypervalent iodine are flourishing1 from the classic non-toxic Dess-Martin periodinane oxidation to synthetic reagents for elaborate natural products2. New types of both iodine(III) and iodine(V) compounds are constantly being discovered for ever increasing applications.

Iodonium salts, classified as iodine(III) compounds, are notoriously electrophilic. Those with two carbon ligands like alkynyl(aryl)iodonium salts react with a nucleophile which couples with the alkyne.  Overall, the reaction seemingly pieces together two nucleophilic entities.

The remaining aryl iodide in the balanced equation seems to be a “spectator” since it is absent in the product, but in this recent (open access) paper Hamnett and Moran sought to investigate whether that is truly the case.

They improved the preparation of alkynyl(aryl)iodonium tosylates and systematically applied them to two model reactions, finding that the 2-anisyl ligand provided the highest yields.

It significantly out-performed the 3-anisyl derivative, suggesting that the key to success is the inherent stability of the 2-anisyl iodonium salt with the methoxy group ideally situated for coordination to the iodine.

Discovering the effectiveness of the 2-anisyl ligand in iodonium salts could have implications for more efficient transformations involving hypervalent iodine.  More broadly, the work shows the importance of optimizing reactions across all variables and highlighting that spectators may not always be simple bystanders.

To find out more see:

Improving alkynyl(aryl)iodonium salts: 2-anisyl as a superior aryl group
David J. Hamnett and Wesley J. Moran
DOI: 10.1039/C4OB00556B


1. M. S. Yusubov, A. V. Maskaev and V. V. Zhdankin, ARKIVOC, 2011, i, 370–409.
2. D. J. Wardrop and J. Fritz, Org. Lett., 2006, 8, 3659–3662.

Posted on behalf of Jennifer Lee, guest web writer for Organic & Biomolecular Chemistry

Jennifer LeeJennifer Lee is currently a Ph.D. candidate in Dr. George Kraus’ organic chemistry lab at Iowa State University. Her research focuses on designing methodologies to transform carbohydrate-derived biomass into biorenewable commodity and specialty chemicals. The creation of a versatile platform technology led to diverse and industrially-relevant aromatic compounds to work toward a more sustainable future.

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OBC Poster Prize winner at ISMSC-9 in Shanghai

Congratulations to Hanna Jędrzejewska from the Polish Academy of Sciences in Warsaw for winning the Organic & Biomolecular Chemistry poster prize awarded at the 9th International Symposium on Macrocyclic and Supramolecular Chemistry (ISMSC-9) held at SIOC, Shanghai, on 7-11 June 2014.

The title of her winning poster was: Chiral self-sorting of hybrid peptidic capsules

Hanna wins a copy of the book Polymeric and Self Assembled Hydrogels : From Fundamental Understanding to Applications, signed by its author, and winner of the 2014 Cram Lehn Pedersen Prize Prof. Oren Scherman.

Hanna Jędrzejewska, OBC Poster Prize winner (right) is presented with a certificate and RSC Book, by Prof. Andrew Wilson (left) and Dr. Marie Cote (OBC Deputy Editor, centre)

On her winning work, Hanna comments:

This project aims at the synthesis of bio-compatible peptidic capsules by means of self-organization of short peptides. Such capsules can be further used for encapsulation, storage and transport of biologically relevant targets. Even though peptides are endowed with natural self-assembling properties, capsules made of short “native” peptides do not form spontaneously due to high conformational lability and tendency to form non-porous random aggregates. I have found that this disadvantage can be overcome by properly designed scaffolds that “guide” peptides into capsular structures. I have used short peptides of various chirality attached in a dynamical covalent way to the macrocyclic skeleton. This way I have obtained building blocks that spontaneously self-sort into porous peptidic capsules resembling closed β-barrels.

I’ve been working on this topic for 1 year. This research is fully supported by the PARENT/BRIDGE programme that enables the best researchers who are raising young children to return to advanced research work. The programme is financed by Foundation for Polish Science within European Regional Development Fund under the Innovative Economy Operational Programme 2007-2013.

Hanna works as a PhD student in the group of Prof. Agnieszka Szumna.

Congratulations again to Hanna – the OBC team whishes her all the very best with her research work!

From left to right: Prof. Zhanting Li, Hanna Jędrzejewska (OBC Poster Prize Winner), Prof. Andrew Wilson, Prof. Oren Scherman, Dr. Robert Eagling, Prof. Jonathan Sessler and Dr Marie Cote

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Recent HOT Organic & Biomolecular Chemistry articles

Polyamine modification by acrolein exclusively produces 1,5-diazacyclooctanes: a previously unrecognized mechanism for acrolein-mediated oxidative stress
Ayumi Tsutsui, Rie Imamaki, Shinobu Kitazume, Shinya Hanashima, Yoshiki Yamaguchi, Masato Kaneda, Shinya Oishi, Nobutaka Fujii, Almira Kurbangalieva, Naoyuki Taniguchi and Katsunori Tanaka  
Org. Biomol. Chem., 2014, Advance Article
DOI: 10.1039/C4OB00761A

Polyamine modification by acrolein exclusively produces 1,5-diazacyclooctanes: a previously unrecognized mechanism for acrolein-mediated oxidative stress

Free to access until 18th July 2014


Catalytic functionalization of tertiary alcohols to fully substituted carbon centres
Long Chen, Xiao-Ping Yin, Cui-Hong Wang and Jian Zhou
Org. Biomol. Chem., 2014, Advance Article
DOI: 10.1039/C4OB00718B

Catalytic functionalization of tertiary alcohols to fully substituted carbon centres

Free to access until 18th July 2014


Pd-catalyzed carbonylation for the construction of tertiary and quaternary carbon centers with sp3 carbon partners
Wei Lu, Yang Li, Chao Wang, Dong Xue, Jian-Gang Chen and Jianliang Xiao
Org. Biomol. Chem., 2014, Advance Article
DOI: 10.1039/C4OB00568F

Pd-catalyzed carbonylation for the construction of tertiary and quaternary carbon centers with sp3 carbon partners

Free to access until 18th July 2014


Asymmetric synthesis of substituted NH-piperidines from chiral amines
Lekh Nath Gautam, Yijin Su, Novruz G. Akhmedov, Jeffrey L. Petersen and Xiaodong Shi  
Org. Biomol. Chem., 2014, Advance Article
DOI: 10.1039/C4OB00657G

Asymmetric synthesis of substituted NH-piperidines from chiral amines

Free to access until 18th July 2014


Evaluation of 4-substituted styrenes as functional monomers for the synthesis of theophylline-specific molecularly imprinted polymers
Hazit Zayas, Clovia I. Holdsworth, Michael C. Bowyer and Adam McCluskey  
Org. Biomol. Chem., 2014, Advance Article
DOI: 10.1039/C4OB00517A

Evaluation of 4-substituted styrenes as functional monomers for the synthesis of theophylline-specific molecularly imprinted polymers

Free to access until 18th July 2014


Synthesis of phosphaisocoumarin amidates via DIBAL-H-mediated selective amidation of phosphaisocoumarin esters
Yu-Juan Guo, Pei-Jiang Chen, Bo Wang and Ai-Yun Peng  
Org. Biomol. Chem., 2014, Advance Article
DOI: 10.1039/C4OB00663A

Synthesis of phosphaisocoumarin amidates via DIBAL-H-mediated selective amidation of phosphaisocoumarin esters

Free to access until 18th July 2014


In(OTf)3-catalysed one-pot versatile pyrrole synthesis through domino annulation of α-oxoketene-N,S-acetals with nitroolefins
Abhijeet Srivastava, Gaurav Shukla, Anugula Nagaraju, Girijesh Kumar Verma, Keshav Raghuvanshi, Raymond C. F. Jones and Maya Shankar Singh  
Org. Biomol. Chem., 2014, Advance Article
DOI: 10.1039/C4OB00781F

In(OTf)3-catalysed one-pot versatile pyrrole synthesis through domino annulation of α-oxoketene-N,S-acetals with nitroolefins

 

Free to access until 18th July 2014


Improving alkynyl(aryl)iodonium salts: 2-anisyl as a superior aryl group
David J. Hamnett and Wesley J. Moran  
Org. Biomol. Chem., 2014,12, 4156-4162
DOI: 10.1039/C4OB00556B

Graphical abstract

Free to access until 4th July 2014


Recent development of two-photon fluorescent probes for bioimaging
Dokyoung Kim, Hye Gun Ryu and Kyo Han Ahn
Org. Biomol. Chem., 2014, Advance Article
DOI: 10.1039/C4OB00431K

Graphical abstract

Free to access until 4th July 2014


A succinyl lysine-based photo-cross-linking peptide probe for Sirtuin 5
Karunakaran A. Kalesh and Edward W. Tate  
Org. Biomol. Chem., 2014,12, 4310-4313
DOI: 10.1039/C4OB00773E

Graphical abstract 

Free to access until 4th July 2014


Marine bacteria from the Roseobacter clade produce sulfur volatiles via amino acid and dimethylsulfoniopropionate catabolism
Nelson L. Brock, Markus Menke, Tim A. Klapschinski and Jeroen S. Dickschat  
Org. Biomol. Chem., 2014,12, 4318-4323
DOI: 10.1039/C4OB00719K

Graphical abstract

Free to access until 4th July 2014


Hydrogen bond directed epoxidation: diastereoselective olefinic oxidation of allylic alcohols and amines
Stephen G. Davies, Ai M. Fletcher and James E. Thomson  
Org. Biomol. Chem., 2014, Advance Article
DOI: 10.1039/C4OB00616J

Graphical abstract

Free to access until 4th July 2014


An intracellularly activatable, fluorogenic probe for cancer imaging
Ruisong Tian, Mingjie Li, Jin Wang, Min Yu, Xiuqi Kong, Yupeng Feng, Zeming Chen, Yuxi Li, Weiqiang Huang, Wenjie Wu and Zhangyong Hong  
Org. Biomol. Chem., 2014, Advance Article
DOI: 10.1039/C4OB00297K

Graphical abstract

Free to access until 4th July 2014


Palladium mediated intramolecular multiple C–X/C–H cross coupling and C–H activation: synthesis of carbazole alkaloids calothrixin B and murrayaquinone A
Srinivasan A. Kaliyaperumal, Shyamapada Banerjee and Syam Kumar U. K.
Org. Biomol. Chem., 2014, Advance Article
DOI: 10.1039/C4OB00493K

Graphical abstract

Free to access until 4th July 2014

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Taking Tips from Nature

“In biomimetic chemistry, we take what we have observed in nature and apply its principles to the invention of novel synthetic compounds that can achieve the same goals….”1

– Ronald Breslow

Biomimetic chemistry is broadly defined as the area of chemistry which aims to imitate the biosynthetic pathways (or parts of the biosynthetic pathways) used by Nature to create chemical bonds.

Just as the fundamental principles of chemistry help us to understand how biological systems work, we can also use biology as an inspiration for developing new chemistry.

Biomimetic chemistry is often used as a method for attempting to prove or disprove proposed biosynthetic pathways; however it can also be used to design laboratory procedures for making synthetic compounds, resulting in reactions which imitate a natural chemical process. For example, elaborate natural products can be more efficiently synthesized in the laboratory by looking at how Nature handles the chemical complexity of such an operation; reaction selectivity can be greatly enhanced by taking tips from how Nature uses enzymes to hold substrates in position while reactions occur.2

α-Amino acids are a fundamental building block in Nature, as the precursors to many biological molecules. In biological systems, amino acids are synthesized from α-ketoacids in a transamination reaction catalysed by the enzyme aminotransferase, with glutamate as the nitrogen source (Scheme 1).3

In this paper, Shi and co-workers seek to mimic this reaction with an enantioselective transamination of α-ketoesters (which can be readily transformed into amino acids) using a substituted benzylamine as the nitrogen source (Scheme 2). The enantioselectivity is induced using chiral base (1, Scheme 2) derived from quinine, a naturally occurring alkaloid which is isolated from the bark of the cinchona tree. This new, biomimetic methodology is highly complementary to the current literature methods for making enantioenriched α-amino acids.

To read more, see;

Organocatalytic Synthesis of Optically Active β-Branched α-Amino Ester via Asymmetric Biomimetic Transamination

Cunxiang Su, Ying Xie, Hongjie Pan, Mao Liu, Hua Tian, Yian Shi, Org. Biomol. Chem., 2014, DOI:10.1039/c4ob00684d.

References

1 R. Breslow, J. Bio. Chem., 2009, 284, 1337.

2 S. France, D. Guerin, S. Miller, T. Lectka, Chem. Rev., 2003, 103, 2985.

3 E. J. Parker, A. J. Pratt, 2010, “Amino Acid Biosynthesis, in Amino Acids, Peptides and Proteins in Organic Chemistry: Building Blocks, Catalysis and Coupling Chemistry”, Volume 3 (ed A. B. Hughes), Wiley-VCH Verlag GmbH & Co.

Dr C. Liana Allen is currently a post-doctoral research associate in the group of Professor Scott Miller at Yale University, where she works on controlling the enantio- or regioselectivity of reactions using small peptide catalysts. Liana received her Ph.D. in organic chemistry at Bath University with Professor Jonathan Williams, where she worked on developing novel, efficient syntheses of amide bonds.

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