One day One Scientist Honoured........PROFESSOR DARREN J. DIXON 14 DEC 2014

PROFESSOR DARREN J. DIXON  

honoured on 14 Dec 2014

The research interests of the Dixon group lie mainly in the field of Organic Synthesis. We focus projects at the intersection between the discovery of new reactions and reactivity, the development of this into powerful synthetic methodology and its application to the total synthesis of natural products and molecules of biological significance. Furthermore we aim to make our chemistry accessible to the majority of organic synthesis chemists by making the reactions technically simple to perform, efficient, scaleable, selective and broad in scope. Our research is supported by a number of pharmaceutical companies (Pfizer, AstraZeneca, GlaxoSmithKline, UCB) largely through the CASE scheme and provides an excellent in-depth training in all aspects of organic synthesis. ‘Hot’ project areas where we have enjoyed significant successes include:asymmetric catalysis (organocatalysis and transition metal ion catalysis), reaction cascade catalysis (promoted by single and mutually compatible multiple catalysts), stereoselective methodology development and complex natural product synthesis.

http://research.chem.ox.ac.uk/darren-dixon.aspx

1. Department of Chemistry, Chemistry Research Laboratory, University of Oxford, Mansfield Road, Oxford OX1 3TA (UK)

Email: Prof. Dr. Darren J. Dixon (darren.dixon@chem.ox.ac.uk)

Department of Chemistry, Chemistry Research Laboratory, University of Oxford, Mansfield Road, Oxford OX1 3TA (UK)

PROFESSOR DARREN J. DIXON

Darren.Dixon@chem.ox.ac.uk

http://research.chem.ox.ac.uk/darren-dixon.aspx.....................

- See more at: http://organicchemistrysite.blogspot.in/#sthash.UFWwgFeS.dpuf

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Indoxamycin B

In 2009 a research group in Japan isolated a novel class of polyketides, subsequently named indoxamycins, from saline cultures of  marine-derived actinomycetes. [1]

Within this family, indoxamycins A and F have been shown to display growth inhibition against HT-29 tumor cell lines (IC50 = 0.59 mm and 0.31 mm, respectively). Their biological activity in conjunction with the highly congested and stereochemically dense core render the indoxamycins notable as targets for synthetic studies.  The absolute and relative stereochemistry of indoxamycins was originally assigned based on a combination of one- and two-dimensional NMR experiments and CD studies.

The indoxamycins skeleton consists of an unprecedented [5,5,6] tricyclic cage-like carbon framework and two side chains having a trisubstituted olefin and an unsaturated carboxylic acid, respectively. The core structure features six contiguous stereogenic centers, of which three are quaternary, including two vicinal carbon atoms embedded in a sterically congested tetrahydrofuran subunit .

In 2012, Carreira and co-workers reported an elegant total synthesis of rac-indoxamycin B, which led to a structural reassignment of the relative configuration at the C2 position and the geometry of the trisubstituted alkene in the side chain.[2]Next year, Ding and coworkers have accomplished total synthesis of indoxamycins A, C, and F in their racemic and enantiomerically pure forms. [3]

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http://www.organic-chemistry.org/Highlights/2012/05November.shtm

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http://brsmblog.com/?p=1108


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http://www.rsc.org/chemistryworld/2012/05/indoxamycin-b

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http://www.rsc.org/chemistryworld/2014/01/organic-matter-brsm-indoxamycins

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References

[1]  “Indoxamycins A−F. Cytotoxic Tricycklic Polypropionates from a Marine-Derived Actinomycete”

Sato, S.  Iwata, F.;  Mukai, T.;  Yamada, S.  Takeo, J.;  Abe, A.  Kawahara, H. J. Org. Chem. 2009, 74, 5502. DOI: 10.1021/jo900667j

Six antitumor antibiotics of a new structure class, indoxamycins A−F (1−6), were isolated from a saline culture group of marine-derived actinomyces whose strains showed approximately 96% sequence homology of 16S rDNA with the family streptomycetaceae. The structures of these indoxamycins, which are unusual polyketides composed of six consecutive chiral centers, were assigned by combined spectral and chemical methods. In feeding experiments using a stable isotope label, indoxamycin A was assembled from propionate units initially forming the “aglycon” pentamethyl indeno furan. The discovery of these unprecedented compounds from marine-derived actinomycetes, a low gene homology genus, offers a significant opportunity for drug discovery.

[2]  “Total Synthesis and Stereochemical Reassignment of (+-)-Indoxamycin B”

Jeker, O. F.; Carreira, E. M. Angew. Chem. Int. Ed. 2012, 51, 3474–3477.

Revised version: The first total synthesis of indoxamycin B leads to a stereochemical reassignment of the natural product (see picture). The synthetic route features an efficient carboannulation sequence to rapidly access the dihydroindenone system. Moreover, a series of AuI-catalyzed transformations served in the construction of the sterically congested core framework.

[3] “Divergent Total Synthesis of Indoxamycins A, C, and F”

He, C.; Zhu, C.; Dai, Z.; Tseng, C.-C.; Ding, H. Angew. Chem. Int. Ed. 2013, 52, 13256–13260. DOI: 10.1002/anie.201307426 

The concise and divergent: total synthesis of (−)-indoxamycins A, C, and F has been completed for the first time by using a tricyclic enone as the common late-stage intermediate. The key steps of the strategy are based on an Ireland–Claisen rearrangement, a stereodivergent reductive 1,6-enyne cyclization, and a tandem 1,2-addition/oxa-Michael/methylenation reaction.

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Abstract

A catalytic asymmetric synthesis of imidazolines with a fully substituted β-carbon atom by a Mannich-type addition/cyclization reaction of isocyanoacetate pronucleophiles and N-diphenylphosphinoyl ketimines has been developed. When a combination of a cinchona-derived aminophosphine precatalyst and silver oxide was employed as a binary catalyst system, good reactivity, high diastereoselectivities (up to 99:1 d.r.), and excellent enantioselectivities (up to 99 % ee) were obtained for a range of substrates.

Direct Catalytic Enantio- and Diastereoselective Mannich Reaction of Isocyanoacetates and Ketimines^†

1. Dr. Irene Ortín and
2. Prof. Dr. Darren J. Dixon^*

Article first published online: 24 FEB 2014

DOI: 10.1002/anie.201309719

Angewandte Chemie International Edition

Volume 53, Issue 13, pages 3462–3465, March 24, 2014

see........http://onlinelibrary.wiley.com/doi/10.1002/anie.201309719/abstract

Ortín, I. and Dixon, D. J. (2014), Direct Catalytic Enantio- and Diastereoselective Mannich Reaction of Isocyanoacetates and Ketimines. Angew. Chem. Int. Ed., 53: 3462–3465. doi: 10.1002/anie.201309719

Author Information

1. Department of Chemistry, Chemistry Research Laboratory, University of Oxford, Mansfield Road, Oxford OX1 3TA (UK)

Email: Prof. Dr. Darren J. Dixon (darren.dixon@chem.ox.ac.uk)

^*Department of Chemistry, Chemistry Research Laboratory, University of Oxford, Mansfield Road, Oxford OX1 3TA (UK)===

Professor Darren J. Dixon

Darren.Dixon@chem.ox.ac.uk

http://research.chem.ox.ac.uk/darren-dixon.aspx

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A route to convert CO2: synthesis of 3,4,5-trisubstituted oxazolones

Green Chem., 2015, Advance Article

DOI: 10.1039/C4GC02033B, Paper

Jiayin Hu, Jun Ma, Zhaofu Zhang, Qinggong Zhu, Huacong Zhou, Wenjing Lu, Buxing Han

CO2 can react with various propargylic amines to form 3,4,5-trisubstituted oxazolones catalyzed by the active, selective and stable ionic liquids.

A route to convert CO2: synthesis of 3,4,5-trisubstituted oxazolones

http://pubs.rsc.org/en/Content/ArticleLanding/2015/GC/C4GC02033B?utm_source=feedburner&utm_medium=feed&utm_campaign=Feed%3A+rss%2FGC+%28RSC+-+Green+Chem.+latest+articles%29#!divAbstract

Production of value-added chemicals using carbon dioxide (CO2) as a feedstock is favorable to the sustainable development of the chemical industry. In this work, we have discovered for the first time that CO2 can react with propargylic amines to produce 3,4,5-trisubstituted oxazolones, a class of very useful chemicals. It was found that the ionic liquid (IL) 1-butyl-3-methylimidazolium acetate ([Bmim][OAc]) can catalyze the reactions efficiently at atmospheric pressure under metal-free conditions. It was also found that [Bmim][OAc] and IL 1-butyl-3-methylimidazolium bis((trifluoromethyl)sulfonyl)imide ([Bmim][Tf2N]) have an excellent synergistic effect for promoting the reactions. The [Bmim][OAc]/[Bmim][Tf2N] catalytic system can be reused at least five times without loss in catalytic activity and selectivity. The reaction mechanism was proposed on the basis of density functional theory (DFT) calculation and the experimental results.

Interview with a Ketamine Chemist

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read this
 http://www.vice.com/read/interview-with-ketamine-chemist-704-v18n2

  http://www.vice.com/read/interview-with-ketamine-chemist-704-v18n2

  http://www.vice.com/read/interview-with-ketamine-chemist-704-v18n2

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