Date of Award
Doctor of Philosophy in Chemistry
The discovery of new synthetic methods and routes for making new bonds is one of the highest incentives to an organic chemist. Innovative, efficient, effective, economical and exceptionally environmentally friendly synthetic methods are being continuously discovered. Transition metal catalyzed C-H activation has been unearthed as one of these methods, especially iron catalyzed direct C-H activation. Fundamental to making more discoveries is understanding the mechanism behind a specific reaction. To this end, the mechanism behind iron catalyzed C-H activation was investigated. Results indicate the intermediary transition state for the iron species involves an Fe(I) species but the attempt to synthesize this Fe(I) species failed. We also confirmed that Fe(II) is definitely not the active species for this reaction. The nitrogen-based ligand might not have afforded us the Fe(I) complexes but there was evidence to show the reduction of the Fe(acac)3 due to the formation of the biphenyl product.
In the same vein of discovery, we identified a mild, one-pot, FeCl2 mediated procedure to produce 3-substituted allylic alcohols from α,β-unsaturated ketones. The addition of an organolithium nucleophile produced tertiary allylic alcohol as an intermediate, which underwent a 1,3-OH migration assisted by FeCl2. The proposed mechanism indicates that a syn-facial migration occurs for the significant product and we obtained yield as high as 98% from this one-pot reaction.
New synthetic methods are also very beneficial to the world outside chemistry. The study of the carcinogen 2-amino--carboline (AαC) and its interaction with DNA involved the synthesis of the AC-DNA adduct. We report the synthesis of AαC and 2-nitro-α-carboline (AαC-NO2) which also facilitate the synthesis of DNA adducts for biophysical studies. An attempt was made to synthesize the fluorinated 2-nitro-α-carboline which will enable the use of 19F-NMR for monitoring of these studies. Cyclization of the coupled product for the fluorinated analogue could not be achieved due to the electron deficiency in the ring systems. AαC was obtained in good yields of 88%, and the AαC-NO2 was obtained in 60% yield.
Oppong, Anita Adjoa, "INVESTIGATION OF IRON MEDIATED MOLECULAR TRANSFORMATIONS AND SYNTHESIS OF 2-AMINO-α-CARBOLINE AND ITS ANALOGUES RELEVANT FOR DNA ADDUCT FORMATION" (2019). Open Access Dissertations. Paper 887.
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