Author ORCID Identifier:
Date of Graduation
12-2025
Document Type
Dissertation
Degree Name
Doctor of Philosophy in Chemistry (PhD)
Degree Level
Graduate
Department
Chemistry & Biochemistry
Advisor/Mentor
Zheng, Nan
Committee Member
Allison, Neil
Second Committee Member
Kilyanek, Stefan
Third Committee Member
Striegler, Susanne
Keywords
Dstonci radical cation; Nitrogen-centered radical; Organic chemistry; Photochemistry; Ring-opening reaction
Abstract
The nitrogen-centered radical has been drawing increasing attention among researchers. Radical polarity is one of the key factors in studying nitrogen-centered radicals’ reactivity, and the functional groups attached to the nitrogen atom are of vital importance. Among different types of nitrogen-centered radicals, aminium radical and metal aminium radical are electrophilic due to the positive charge on the intermediate. The sulfonamide radical, amidyl radical, and cyanide amine radical are also electrophilic since the nitrogen is adjacent to electron electron-withdrawing group. The neutral amino radical, iminyl radical, masked nitrogen radical are nucleophilic because of the electron-donating groups. After classifying the nitrogen-centered radical, the generation and reactivity of these radicals are discussed in detail. One of the thesis projects is the spiro cyclic aminal photocatalytic ring-opening and monofunctionalization via distonic radical cation. The existing aminium radical studies mainly focus on the [3+2] annulation reactions, and the only exceptional example is the photocatalytic ring-opening and difunctionalization study with TMSCN from our group’s unpublished result. TMSCN helps to stabilize the aminium side of the radical cation to push the reaction forward. Inspired by the rearrangement reactivity of the cyclic aminal studies, we propose that the aminal can also help to stabilize the aminium side of the photocatalytic-generated distonic radical cation. The aminal photocatalytic ring-opening and monofunctionalization works well with the radical acceptor, many trifluoromethyl styrenes, and some variations on the aminal ring and cyclobutanone can also be achieved. The other project refers to photocatalytic ring-opening and monofunctionalization of the spiro hydro-benzoxazine featured with the N, O-acetal structure. Although designed to stabilize the distonic radical cation using the N, O-acetal, the reaction seems to go through the PCET pathway.In this case, the nickel-catalyzed C(sp2)-C(sp3) cross-coupling is tested to figure out whether it can fit in the PCET nitrogen neutral radical ring-opening system. The study gives another possible reactivity other than alkene addition, which is well-explored in the existing cyclic alkyl amine ring-opening studies. The optimization of the reaction is done, and further scope extension reveals more effect in the future study.
Citation
Zhou, C. (2025). Ring-opening and Monofunctionalization Study on Spiro Cyclic Aminals and N, O-acetals System via Nitrogen-centered Radical Intermediates. Graduate Theses and Dissertations Retrieved from https://scholarworks.uark.edu/etd/6067
