Stereoselective nickel-catalysed arylative cyclisation reactions

Panchal, Heena (2019) Stereoselective nickel-catalysed arylative cyclisation reactions. PhD thesis, University of Nottingham.

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Abstract

Chapter 1: Indanes and their derivatives are a common unit in a range of biologically active scaffolds. Numerous approaches have been reported for the synthesis of these scaffolds. Annulation reactions between ortho-functionalised aryl aldehydes or ketones with various unsaturated reaction partners provide a useful approach towards indenols. Herein, the synthesis of 3-methyleneindan-1-ols using nickel catalysis is reported. The reaction between activated allenes and 2-acylarylboronic acids generates the products in generally good yields and excellent diastereoselectivities. This methodology allows access to products with fully substituted olefins, and adjacent quaternary centres. The reaction can be effectively scaled up, the catalyst loading decreased, and enantioselectivity can be induced via the addition of a chiral ligand.

Chapter 2: Cyclopentenones appear in a number of biologically active compounds, agrochemicals, and natural products. As a result, numerous methods have been developed for their synthesis, with the Pauson-Khand and Nazarov reactions being perhaps the most well known. Each method presents its own set of unique advantages and challenges, and with the scaffold present in a diverse range of compound classes, new strategies for their synthesis remain valuable. Herein, the synthesis of chiral cyclopent-2-enones via the enantioselective desymmetrisation of malonate esters by arylative cyclisations is reported. This allows for the generation of highly substituted cyclopent-2-enones with an α-quaternary centre. The cyclisation reactions proceed efficiently with a nickel-catalyst and chiral phosphinooxazoline ligand, enabled by the reversible E/Z isomerisation of the alkenylnickel species. A range of substituents at the α-position, alkyne, and on the boronic acids are well tolerated, affording chiral cyclopent-2-enones in excellent yields and enantioselectivities. The reaction can be effectively scaled up, and the products manipulated to generate amides and alcohols.

Item Type: Thesis (University of Nottingham only) (PhD)
Supervisors: Lam, Hon Wai
Keywords: Nickel catalysis
Subjects: Q Science > QD Chemistry
Faculties/Schools: UK Campuses > Faculty of Science > School of Chemistry
Item ID: 56135
Depositing User: Panchal, Heena
Date Deposited: 17 Jul 2019 04:40
Last Modified: 07 May 2020 12:17
URI: http://eprints.nottingham.ac.uk/id/eprint/56135

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