"N"-Heterocyclic Carbene-Catalyzed Reaction of Chalcone and Cinnamaldehyde to Give 1,3,4-Triphenylcyclopentene Using Organocatalysis to Form a Homoenolate Equivalent

Autor/in	Snider, Barry B.
Titel	"N"-Heterocyclic Carbene-Catalyzed Reaction of Chalcone and Cinnamaldehyde to Give 1,3,4-Triphenylcyclopentene Using Organocatalysis to Form a Homoenolate Equivalent
Quelle	In: Journal of Chemical Education, 92 (2015) 8, S.1394-1397 (4 Seiten)Infoseite zur Zeitschrift PDF als Volltext Verfügbarkeit
Sprache	englisch
Dokumenttyp	gedruckt; online; Zeitschriftenaufsatz
ISSN	0021-9584
DOI	10.1021/acs.jchemed.5b00105
Schlagwörter	Leitfaden; Unterricht; Lehrer; Science Instruction; Science Experiments; Scientific Concepts; College Science; Organic Chemistry; Hands on Science; Spectroscopy; Computer Assisted Instruction; Science Laboratories; Laboratory Experiments; Massachusetts + Suchen Sie Ihr Suchwort? Lesson concept; Instruction; Unterrichtsentwurf; Unterrichtsprozess; Teacher; Teachers; Lehrerin; Lehrende; Teaching of science; Science education; Natural sciences Lessons; Naturwissenschaftlicher Unterricht; Organische Chemie; Spektroskopie; Computer based training; Computerunterstützter Unterricht; Laboratory work; Laborarbeit; Master-Studiengang
Abstract	In this experiment, students carry out a modern organocatalytic reaction using IMes·HCl and NaOH to catalyze the formation of 1,3,4-triphenylcyclopentene from cinnamaldehyde and chalcone in water. Deprotonation of IMes·HCl with NaOH forms the "N"-heterocyclic carbene IMes that reacts with cinnamaldehyde to form a homoenolate equivalent of cinnamate, which undergoes a conjugate addition to chalcone followed by an intramolecular aldol reaction to form a cyclopentane. Formation of a ß-lactone and decarboxylation leads to 1,3,4-triphenylcyclopentene. This reaction introduces students to both organocatalysis and the use of carbonyl anion and homoenolate equivalents in synthesis. This novel and interesting chemistry was first reported in 2006, and the reaction was modified to be carried out in water under an air atmosphere in 2013. The very nonpolar product is easily purified chromatographically. The aliphatic protons form a somewhat complex pattern due to allylic and homoallylic coupling, but with no overlap, so that students can simulate the spectrum perfectly using Web-based software. This experiment can be combined with one of the four preparations of IMes·HCl reported in this Journal, which all use IMes as a ligand rather than an organocatalyst. (As Provided).
Anmerkungen	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
Erfasst von	ERIC (Education Resources Information Center), Washington, DC
Update	2020/1/01