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Title: New reactions of lithiated aziridines and pyrrolidines : applications in nitrogen heterocycle synthesis
Author: Moore, Stephen
ISNI:       0000 0001 3418 6905
Awarding Body: University of York
Current Institution: University of York
Date of Award: 2008
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This PhD thesis describes the original developments of new reactions of lithiated aziridines and pyrrolidines and their use in nitrogen heterocycle synthesis. Chapter one represents a comprehensive overview of the literature covering the different modes of reactivity of lithiated epoxides and aziridines. These include: (i) carbenoid insertion into CH bonds and transannular CH bond insertions, (ii) carbenoid insertion into organolithium reagents (also known as reductive alkylation) and (iii) electrophilic trapping. Chapter two describes the development of a new route to aza-spirocycle-containing compounds using reductive alkylation as a key step. Thus, the reductive alkylation of a range of cyclic substituted p-methoxy aziridines gave high yields of allylic sulfonamides, which were converted into aza-spirocycles using a two-step hydroboration-Mitsunobu protocol. This included our work towards the synthesis of the aza-spirocycle-containing natural product, (±)-cephalotaxine. Chapter three describes the diastereoselective synthesis and organolithium-mediated reactions of a range of p-methoxy aziridines derived from acyclic alkenes. This included a Z-stereoselective reductive alkylation and a novel alkyne forming reaction. The preparation of a N-2,4,6-triisopropylbenzenesulfonyl (Tris) p-methoxy aziridine was also carried out. Chapter four represents the development of a new route for the asymmetric synthesis of 2,3-substituted piperidines. First, the asymmetric lithiation-aldehyde trapping ofNBoc pyrrolidine gave the corresponding amino alcohols with high enantioselectivity and diastereoselectivity. Second, the ring expansion from pyrrolidines to piperidines was carried out. This included a total synthesis of the pharmaceutical (+)-L-733,060 and a formal synthesis of the natural product (+)-swainsonine. A brief overview ofthe literature covering these topics is also included.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available