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1,1,1-Trifluoropropan-2-ammonium triflate enantiomers: stereoselective synthesis and direct use in reaction with epoxides

1,1,1-Trifluoropropan-2-ammonium triflate enantiomers: stereoselective synthesis and direct use in reaction with epoxides
1,1,1-Trifluoropropan-2-ammonium triflate enantiomers: stereoselective synthesis and direct use in reaction with epoxides
A three-step synthesis of enantiomerically enriched 1,1,1-trifluoro-2-propanamine based on the use of a chiral sulfinamide auxiliary is described. The reduction of the geometrically pure Z-sulfinimine (NOE, HOE) with NaBH4 or L-Selectride leads to the corresponding (R)- or (S)-configured amine derivatives (X-ray crystallographic analysis) with 92–96% de. The typical models to explain the stereoselection for these reducing agents fail to rationalize the obtained stereoselectivities, and an in situ imine isomerization is proposed to occur. The direct use of the hydrochloric acid salt (with excess Et3N) of this poorly nucleophilic amine for epoxide opening reactions is not possible due to the higher nucleophilicity of chloride. Hence, a novel triflate salt is introduced, synthesized through ready sulfinamide hydrolysis with trimethylsilyl triflate, which can be used directly, without the need of isolating the pure amine beforehand.
Packer, Gemma
15400986-1ca0-4f24-81f0-ecbe79675266
Malassis, Julien
5cd4224d-e4db-4835-863c-56b709511ccd
Wells, Neil
86312185-007b-495b-86da-4e2e5b9b8025
Light, Mark
cf57314e-6856-491b-a8d2-2dffc452e161
Linclau, Bruno
19b9cacd-b8e8-4c65-af36-6352cade84ba
Packer, Gemma
15400986-1ca0-4f24-81f0-ecbe79675266
Malassis, Julien
5cd4224d-e4db-4835-863c-56b709511ccd
Wells, Neil
86312185-007b-495b-86da-4e2e5b9b8025
Light, Mark
cf57314e-6856-491b-a8d2-2dffc452e161
Linclau, Bruno
19b9cacd-b8e8-4c65-af36-6352cade84ba

Packer, Gemma, Malassis, Julien, Wells, Neil, Light, Mark and Linclau, Bruno (2017) 1,1,1-Trifluoropropan-2-ammonium triflate enantiomers: stereoselective synthesis and direct use in reaction with epoxides. Tetrahedron: Asymmetry. (doi:10.1016/j.tetasy.2017.03.003). (In Press)

Record type: Article

Abstract

A three-step synthesis of enantiomerically enriched 1,1,1-trifluoro-2-propanamine based on the use of a chiral sulfinamide auxiliary is described. The reduction of the geometrically pure Z-sulfinimine (NOE, HOE) with NaBH4 or L-Selectride leads to the corresponding (R)- or (S)-configured amine derivatives (X-ray crystallographic analysis) with 92–96% de. The typical models to explain the stereoselection for these reducing agents fail to rationalize the obtained stereoselectivities, and an in situ imine isomerization is proposed to occur. The direct use of the hydrochloric acid salt (with excess Et3N) of this poorly nucleophilic amine for epoxide opening reactions is not possible due to the higher nucleophilicity of chloride. Hence, a novel triflate salt is introduced, synthesized through ready sulfinamide hydrolysis with trimethylsilyl triflate, which can be used directly, without the need of isolating the pure amine beforehand.

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Linclau manuscript Tet As_revision v2 - Accepted Manuscript
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Accepted/In Press date: 6 March 2017
Organisations: Characterisation and Analytics, Chemistry, Organic Chemistry: SCF

Identifiers

Local EPrints ID: 406988
URI: http://eprints.soton.ac.uk/id/eprint/406988
PURE UUID: dd26ea16-a31d-4ed7-b0a2-1bf956c77964
ORCID for Neil Wells: ORCID iD orcid.org/0000-0002-4607-5791
ORCID for Mark Light: ORCID iD orcid.org/0000-0002-0585-0843
ORCID for Bruno Linclau: ORCID iD orcid.org/0000-0001-8762-0170

Catalogue record

Date deposited: 29 Mar 2017 01:07
Last modified: 07 Oct 2020 05:17

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Contributors

Author: Gemma Packer
Author: Julien Malassis
Author: Neil Wells ORCID iD
Author: Mark Light ORCID iD
Author: Bruno Linclau ORCID iD

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