Presentation Title

Photoinduced Oxidative Cyclization Reactions for the Preparation of Complex Ring Systems

Faculty Mentor

Dr. Peter de Lijser

Start Date

18-11-2017 10:00 AM

End Date

18-11-2017 11:00 AM

Location

BSC-Ursa Minor 116

Session

Poster 1

Type of Presentation

Poster

Subject Area

physical_mathematical_sciences

Abstract

The use of oxidative cyclization with radical or radical ion intermediates is a potentially useful and efficient strategy to achieve the synthesis of novel heteroaromatic structures. Oxime ethers with built in aromatic groups have been shown to undergo a cyclization reaction in which the aromatic ring acts a nucleophile attacking the oxime ether radical cation. Using this same methodology, aromatic nucleophiles with built in heteroatoms could lead to potential new synthetic pathways of interesting and complicated heteroaromatic ring systems. To determine whether heteroaromatic rings can be used as nucleophiles under oxidative cyclization conditions, we prepared a series of benzaldehyde oximes and oxime ethers substituted with heteroaromatics rings containing nitrogen, oxygen, and sulfur. The purified oximes and oxime ethers were subjected to photooxidation processes in controlled conditions and were monitored by GC/MS and NMR for product formation. The result from these studies suggest that the oximes formed their parent aldehydes but did not show signs of cyclization. Several oxime ethers were found to yield what is believed to be a cyclized product via nucleophilic attack by the heteroaromatic ring on the nitrogen of the oxime ether. The most promising results were obtained with the thiophenyl derivatives of the oxime ethers. To further determine if the thiophenyl oxime ether derivatives did in fact cyclize, the reactions were optimized and the products were isolated and characterized. The thiophenyl and furanyl oxime ether reactions are being further quantified using NMR internal standards.

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Nov 18th, 10:00 AM Nov 18th, 11:00 AM

Photoinduced Oxidative Cyclization Reactions for the Preparation of Complex Ring Systems

BSC-Ursa Minor 116

The use of oxidative cyclization with radical or radical ion intermediates is a potentially useful and efficient strategy to achieve the synthesis of novel heteroaromatic structures. Oxime ethers with built in aromatic groups have been shown to undergo a cyclization reaction in which the aromatic ring acts a nucleophile attacking the oxime ether radical cation. Using this same methodology, aromatic nucleophiles with built in heteroatoms could lead to potential new synthetic pathways of interesting and complicated heteroaromatic ring systems. To determine whether heteroaromatic rings can be used as nucleophiles under oxidative cyclization conditions, we prepared a series of benzaldehyde oximes and oxime ethers substituted with heteroaromatics rings containing nitrogen, oxygen, and sulfur. The purified oximes and oxime ethers were subjected to photooxidation processes in controlled conditions and were monitored by GC/MS and NMR for product formation. The result from these studies suggest that the oximes formed their parent aldehydes but did not show signs of cyclization. Several oxime ethers were found to yield what is believed to be a cyclized product via nucleophilic attack by the heteroaromatic ring on the nitrogen of the oxime ether. The most promising results were obtained with the thiophenyl derivatives of the oxime ethers. To further determine if the thiophenyl oxime ether derivatives did in fact cyclize, the reactions were optimized and the products were isolated and characterized. The thiophenyl and furanyl oxime ether reactions are being further quantified using NMR internal standards.