Diastereoselective cyclopropanations of alpha,beta-unsaturated ketals derived from chiral hydrobenzoin
AuthorTorok, Daniel Seth, 1963-
AdvisorMash, Gene A.
MetadataShow full item record
PublisherThe University of Arizona.
RightsCopyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author.
Abstract2-Cycloalken-1-one-(-)-erythro-hydrobenzoin ketals undergo efficient and diastereoselective cyclopropanation when treated with an excess of Simmons-Smith reagent. The resulting crystalline products yield enantiomerically pure cyclopropyl compounds upon recrystallization. For example, 2-cyclohexen-1-one-(-)-erythro-hydrobenzoin ketal gave, in 90% yield, a 19:1 mixture of diastereomeric cyclopropanes as established by 62.9 MHz ¹³C NMR spectroscopy. Upon one recrystallization, diastereomerically pure cyclopropane was obtained in 78% recovery. Hydrolysis gave (+)-norcaranone of greater than 99% ee. Three other examples are presented which demonstrate the advantages of hydrobenzoin ketals over previously used homochiral ketals, as well as several techniques for the synthesis of chiral hydrobenzoin.
Degree ProgramGraduate College