Date of Award
Master of Science in Medicinal Chemistry
Two types of reactions were used to study the effect of substituents (CH3, OCH3) on the condensation of 5(6) substituted benzofurazan 1-oxides (1) with (methylthio)-2-propanone (BFO Reaction, A), and 4- substituted o-quinone dioximes (2) with pyruvaldhyde (OQD Reaction, B). The nitrogen atom is an electrophile in reaction A and nucleophile in reaction B.
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Thus, the same substituent is expected and does favor the formation of opposite ratios of 6:7 isomeric substituted quinoxaline hydroxamic acid esters (3). The ratios were determined from nmr spectra of these esters where the chemical shifts of the H-5 and H-8 protons, unlike their counterparts in quinoxaline 1, 4- dioxides, are assignable. The results are interpreted by assuming that benzofurazan 1-oxides react in their o-dinitroso tautomeric forms.
Alteri, Nicholas D. Jr., "Quinoxaline 1, 4-Dioxides. A Mechanistic Study of Their Formation and the Structural Assignment of 6(7) Isomeric Products" (1974). Open Access Master's Theses. Paper 1119.