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Catalytic Functionalisation of sp3 Bonds

Walton, Scarlett Maria (2017) Catalytic Functionalisation of sp3 Bonds. Doctoral thesis, University of Huddersfield.

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Abstract

Reported herein is an investigation into palladium-catalysed -allylation employing sulfonamide nucleophiles. Anions of benzylsulfonamides have been shown to react with a series of allyl acetates in the presence of Pd0 catalysts, phosphine ligands and base at room temperature, enabling the synthesis of sp3-functionalised sulfonamides. The developed methodology has allowed access to a library of novel allylated sulfonamides, varying both amine substituent and allylic functionality. In addition, we have applied our methodology to a series of known sulfonamide drug targets, to demonstrate our reaction as a useful late-stage functionalisation tool, whilst populating chemical space.

The performed mechanistic study using a stereospecific electrophile confirms benzylsulfonamides behave as soft carbon nucleophiles in the Tsuji-Trost reaction, as a ‘net retention’ of stereochemistry is observed (confirmed by X-ray crystallography).

Moreover, the asymmetric synthesis of allylated sulfonamides is probed, although obtaining enantioselectivity a- to SO bonds is naturally difficult, due to the conformational preferences of sulfonamide carbanions.

Traditional methods for direct -alkylation of sulfonamides require strong bases, reactive electrophiles, low temperatures and use of stoichiometric amounts of additives. Therefore, in addition to a catalytic method, we report an alternative method reacting benzylsulfonamides with allyl bromide electrophiles via a nucleophilic substitution reaction, using mild conditions (LDA, THF at –20 °C).

Item Type: Thesis (Doctoral)
Subjects: Q Science > QD Chemistry
Schools: School of Applied Sciences
Depositing User: Jonathan Cook
Date Deposited: 16 Jan 2018 15:28
Last Modified: 26 Mar 2018 15:16
URI: http://eprints.hud.ac.uk/id/eprint/34344

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