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Title: Organic Brønsted acid-catalysed enantioselective N-acyliminium cyclisation cascades
Author: Muratore, Michael Eric
ISNI:       0000 0004 2743 7448
Awarding Body: University of Oxford
Current Institution: University of Oxford
Date of Award: 2010
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This thesis concerns the development of the first BINOL phosphoric acid (BPA) catalysed enantioselective N-acyliminium cyclisation reactions and their incorporation into domino sequences that allow for the construction of architecturally complex enantioenriched polycycles in a single step from easily accessible starting materials. More specifically, this thesis deals with the discovery of a BPA-catalysed enantioselective N-acyliminium cyclisation cascade of enol lactones and tryptamines. Its extension to a doubly catalysed process involving gold(I) to cycloisomerise alkynoic acids and a BPA to effect the enantioselective N-acyliminium cyclisation is presented. In addition, the exploitation of this method in highly diastereo- and enantioselective N-acyliminium cyclisations of oxoacids and tryptamines and in a site isolated base-catalysed Michael addition / acid-catalysed N-acyliminium cyclisation cascade is described. A study on the proposed mechanism and model for the origin of enantioselectivity is discussed, based on experimental data and a computational study. As a separate part of our programme, the development of a new class of stronger Brønsted acids, chiral benzenesulphonic acids, is described. The optimisation of the synthetic routes as well as the synthesis of a library of acids is presented and their assessment in precedented reactions is discussed.
Supervisor: Dixon, Darren J. Sponsor: EPSRC ; Pfizer
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available
Keywords: Organic chemistry ; Asymmetric catalysis ; Bronsted ; organocatalysis ; enantioselective ; asymmetric ; binol ; phosphoric ; acid ; N-acyliminium ; indole ; cyclisation ; cascade