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ERIC Number: EJ923706
Record Type: Journal
Publication Date: 2011-Feb
Pages: 3
Abstractor: As Provided
Reference Count: 13
ISBN: N/A
ISSN: ISSN-0021-9584
Benzoylation of Ergosterol through Nucleophilic Acyl Substitution and Subsequent Formation of Ergosterol Benzoate Endoperoxide by Reaction with Singlet Oxygen Generated by Photosensitization
Roslaniec, Mary C.; Sanford, Elizabeth M.
Journal of Chemical Education, v88 n2 p229-231 Feb 2011
Reactive oxygen species such as singlet oxygen have been a major focus of research in medicine. The effect of singlet oxygen on sterols within biological membranes is becoming increasingly more important. Ergosterol, a vitamin D precursor, is one such sterol. The benzoylation of ergosterol and subsequent reaction with singlet oxygen to form an endoperoxide provide two important reactions for the undergraduate laboratory. The benzoylation of ergosterol coordinates well with carboxylic acid chemistry generally covered in introductory organic chemistry. The photooxidation of ergosterol benzoate provides a unique dienophile for a [4 + 2] cycloaddition reaction. Singlet oxygen, generated by photosensitization, adds to the diene of the B ring of the sterol. Two explanations for the photosensitization are provided. The first explanation is for introductory organic chemistry students. The second explanation is for upper-level students and delves into electronic states and energy transfer. An optional microscale photosensitization is given using a laser pointer as a light source. This two-step synthesis augments lecture material while providing students the opportunity to develop pertinent laboratory skills including UV-vis and NMR spectroscopy, photochemistry, and TLC and column chromatography. (Contains 2 schemes.)
Division of Chemical Education, Inc and ACS Publications Division of the American Chemical Society. 1155 Sixteenth Street NW, Washington, DC 20036. Tel: 800-227-5558; Tel: 202-872-4600; e-mail: eic@jce.acs.org; Web site: http://pubs.acs.org/jchemeduc
Publication Type: Journal Articles; Reports - Descriptive
Education Level: Higher Education
Audience: Teachers
Language: English
Sponsor: N/A
Authoring Institution: N/A