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Title: The metallocarbene route to heterocyclic compounds
Author: Miah, Soyfur
Awarding Body: Loughborough University
Current Institution: Loughborough University
Date of Award: 1997
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The use of intramolecular aromatic substitution reactions of metallocarbenes derived from α-diazocarbonyl substrates for the preparation of benzo-fused heterocyclic compounds is reviewed. The preparation and metal catalysed decomposition of selected d1azomalonamide esters is outlined. These, and other compounds described, are designed to explore several competing carbenoid reaction pathways, each leading to a different heterocyclic product. Dramatic ligand effects are reported and other factors influencing selectivity are discussed. The use of rhodium(ll) perfluorocarboxamides for highly efficient preparation of oxindoles, via the intramolecular aromatic substitution reaction, was established. The methodology developed for oxindole preparation from diazoamides is exploited in the synthesis of the novel marine alkaloid convolutamydine C, in 8 or 10 steps from 3,5-dibromobenzoic acid. Synthetic studies towards the total synthesis of the uvarindole alkaloids are reported, with the key steps being formation of an oxindole from a diazomalonamide and elaboration in 3 steps to a 1 ,3-dibenzylindole. Efforts to explore the possibility of diastereoselectivity in the intramolecular Buchner reaction (IMBR) are reported. Chiral diazomalonamides proved to be poor substrates for this reaction, probably due to conformational effects. Excellent levels of diastereocontrol were observed with chiral diazomalonates, but the recovery of diastereomerically pure products was found to be modest. Attempts to improve the yield of I MBR products are described. Full experimental details for the synthetic studies are included. X-Ray crystallographic data for selected a-diazocarbonyl substrates and products from their metal catalysed decomposition are appended.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available