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Optimisation and Scope of a Palladium-Catalysed Allylic Alkylation Cascade

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Version 1 2021-11-22, 21:52
thesis
posted on 2023-09-26, 01:35 authored by Matthew Fisk

The design and development of new chemical reactions is crucial for progress in organic synthesis research. Cascade reactions, involving two or more steps carried out in situ in a single pot, provide a step-efficient and atom-economic route to synthesise polycyclic ring systems. The synthesis of new heterocyclic ring systems provides valuable routes towards complex natural products. Previous work in the Harvey group led to the development of a regioselective palladium-catalysed allylic alkylation (Pd-AA) cascade. This research aims to expand the scope and utility of this existing Pd-AA cascade, by optimising the current reaction conditions and exploring a range of non-symmetric pyran-based bis-electrophiles and nitrogen and sulfur-based β-carbonyl bis-nucleophiles.  Isomeric 2,3-unsaturated silyl glycosides based on D-glucose and D-galactose were successfully synthesised. These substrates were assessed as bis-electrophiles in the Pd-AA cascade. The yield of the cascade was successfully optimised with the glucose-derived substrate 4-hydroxy-6-methylpyran-2-one, using Pd₂(dba)₃ and Xantphos, to 87% from the previously reported 77% yield. However, the galactose-derived silyl glycoside formed an undesired pyranone as the major product. Additionally, a series of β-dicarbonyl compounds (4-hydroxy-6-methylpyran-2-one analogues) were assessed as bis-nucleophiles in the Pd-AA cascade, with all of the analogues forming complex mixtures of side products and a fully unsaturated pyranone as the major isolated product.

History

Copyright Date

2017-01-01

Date of Award

2017-01-01

Publisher

Te Herenga Waka—Victoria University of Wellington

Rights License

CC BY-NC-SA 4.0

Degree Discipline

Chemistry

Degree Grantor

Te Herenga Waka—Victoria University of Wellington

Degree Level

Masters

Degree Name

Master of Science

ANZSRC Type Of Activity code

970103 Expanding Knowledge in the Chemical Sciences

Victoria University of Wellington Item Type

Awarded Research Masters Thesis

Language

en_NZ

Victoria University of Wellington School

School of Chemical and Physical Sciences

Advisors

Harvey, Joanne