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4 results on '"Allylic ammonium ylides"'

1. Isothiourea-catalysed chemo- and enantioselective [2,3]-sigmatropic rearrangements of N,N-diallyl allylic ammonium ylides.

Author

West, Thomas H., Spoehrle, Stéphanie S.M., and Smith, Andrew D.

Subjects
*ENANTIOSELECTIVE catalysis, *HETEROGENEOUS catalysis, *SIGMATROPIC rearrangements, *ENANTIOMERS, *OPTICAL isomers
Abstract

The isothiourea-catalysed chemo- and enantioselective [2,3]-sigmatropic rearrangement of N , N -diallyl allylic ammonium ylides is explored as a key part of a route to free functionalised α-amino esters and piperidines. The [2,3]-sigmatropic rearrangement proceeds with excellent diastereo- and enantiocontrol (>95:5 dr, up to 97% ee), with the resultant N , N -diallyl α-amino esters undergoing either mono - or bis - N -allyl deprotection. Bis - N -allyl deprotection leads to free α-amino esters, while the mono-deprotection strategy has been utilized in the synthesis of a target functionalised piperidine. [ABSTRACT FROM AUTHOR]

Published
2017
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2. Enantioselective Synthesis of β-Fluoro-β-aryl-α-aminopentenamides by Organocatalytic [2,3]-Sigmatropic Rearrangement

Author

Kevin Kasten, Andrew D. Smith, Alexandra M. Z. Slawin, European Commission, The Royal Society, University of St Andrews. School of Chemistry, University of St Andrews. EaSTCHEM, and University of St Andrews. Biomedical Sciences Research Complex

Subjects
Allylic ammonium ylides, Stereochemistry, 2,3-sigmatropic rearrangement, Substituent, Medicinal chemistry, 010402 general chemistry, Straightforward, 01 natural sciences, Biochemistry, Stereocenter, Kinetic resolution, Benzotetramisole, chemistry.chemical_compound, Benzylamine, QD, Physical and Theoretical Chemistry, Cycloaddition, Catalysts, 010405 organic chemistry, Chemistry, Aryl, Organic Chemistry, Enantioselective synthesis, Mannich, DAS, QD Chemistry, 0104 chemical sciences, Protein design, Flluorinated amino-acids
Abstract

The research leading to these results (K.K.) has received funding from the ERC under the European Union's Seventh Framework Programme (FP7/2007-2013) / ERC grant agreement n° 279850. A.D.S. thanks the Royal Society for a Wolfson Research Merit Award. The tetramisole-promoted catalytic enantioselective [2,3]-sigmatropic rearrangement of quaternary ammonium salts bearing a (Z)-3-fluoro-3-arylprop-2-ene group generates, after addition of benzylamine, a range of β-fluoro-β-aryl-α-aminopentenamides containing a stereogenic tertiary fluorine substituent. Cyclic and acyclic nitrogen substituents as well as various aromatic substituents are tolerated, giving the β-fluoro-β-aryl-α-aminopentenamide products in up to 76% yield, 96:4 dr, and 98:2 er. Postprint

Published
2017

3. Isothiourea-catalysed chemo- and enantioselective [2,3]-sigmatropic rearrangements of N,N-diallyl allylic ammonium ylides

Author

Andrew D. Smith, Stephanie S. M. Spoehrle, Thomas H. West, European Commission, The Royal Society, University of St Andrews. School of Chemistry, University of St Andrews. EaSTCHEM, and University of St Andrews. Biomedical Sciences Research Complex

Subjects
Allylic rearrangement, Allylic ammonium ylides, 010405 organic chemistry, Organic Chemistry, Enantioselective synthesis, DAS, Sigmatropic reaction, [2,3]-rearrangement, 010402 general chemistry, QD Chemistry, 01 natural sciences, Biochemistry, Isothiourea catalysis, 0104 chemical sciences, chemistry.chemical_compound, chemistry, α-amino esters, Drug Discovery, Organic chemistry, Ammonium, QD, Piperidine, Enantioselective catalysis
Abstract

The research leading to these results (T.H.W.) has received funding from the ERC under the European Union's Seventh Framework Programme (FP7/2007–2013)/E.R.C. grant agreement n° 279850 and the European Union (Marie Curie ITN “SubiCat” PITN-GA-2013-607044) (S. S. M. S.). A.D.S. thanks the Royal Society for a Wolfson Research Merit Award. The data underpinning this publication can be found at DOI: http://dx.doi.org/10.17630/f522b48d-ed02–42b3-a161-54687ea5af57 The isothiourea-catalysed chemo- and enantioselective [2,3]-sigmatropic rearrangement of N,N-diallyl allylic ammonium ylides is explored as a key part of a route to free functionalised α-amino esters and piperidines. The [2,3]-sigmatropic rearrangement proceeds with excellent diastereo- and enantiocontrol (>95:5 dr, up to 97% ee), with the resultant N,N-diallyl α-amino esters undergoing either mono- or bis-N-allyl deprotection. Bis-N-allyl deprotection leads to free α-amino esters, while the mono-deprotection strategy has been utilized in the synthesis of a target functionalised piperidine. Postprint

Published
2017

4. Catalytic stereoselective [2,3]-rearrangement reactions

Author

Andrew D. Smith, Kevin Kasten, Thomas H. West, James E. Taylor, Stephanie S. M. Spoehrle, Marie Curie Fellowships, The Royal Society, University of St Andrews. School of Chemistry, University of St Andrews. Biomedical Sciences Research Complex, and University of St Andrews. EaSTCHEM

Subjects
Stereoselective catalysis, Allylic rearrangement, Allylic N-oxides, Allylic ammonium ylides, Allylic oxonium ylides, Reactive intermediate, NDAS, General Chemistry, [2,3]-rearrangement, O-propargylic oximes, QD Chemistry, Catalysis, chemistry.chemical_compound, Allylic sulfoxides, chemistry, Organic chemistry, Organic synthesis, Stereoselectivity, QD
Abstract

The authors thank the Royal Society for a University Research Fellowship (A.D.S.), the European Research Council under the European Union’s Seventh Framework Programme (FP7/2007-20013) ERC Grant Agreement No. 279850 (J.E.T., T.H.W., K.K.), and the European Union (Marie Curie ITN ‘SuBiCat’ PITN-GA-2013-607044) (S.S.M.S.) for financial support. [2,3]-Sigmatropic rearrangement processes of allylic ylides or their equivalents can be applied to a variety of different substrates and generate products of wide interest and applicability to organic synthesis. This review describes the development and applications of stereoselective [2,3]-rearrangement reactions in which a sub-stoichiometric amount of a catalyst is used in either the formation of the reactive intermediate or the [2,3]-rearrangement step itself. Postprint

Published
2015

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