If you have an ACS member number, please enter it here so we can link this account to your membership. (optional)

ACS values your privacy. By submitting your information, you are gaining access to C&EN and subscribing to our weekly newsletter. We use the information you provide to make your reading experience better, and we will never sell your data to third party members.



Chiral Sulfide Boosts Ylide Chemistry

Inexpensive isothiocineole demonstrates high selectivity in asymmetric syntheses of epoxides and aziridines

by Bethany Halford
February 8, 2010 | A version of this story appeared in Volume 88, Issue 6

Sulfur ylides can be used in the asymmetric syntheses of epoxides and aziridines, but they rarely are because the reactions haven’t been capable of producing synthetically useful compounds with high diastereo- and enantioselectivity. Furthermore, the strategy usually requires a tedious multistep synthesis to make a chiral sulfide as the ylide precursor. Now, Varinder K. Aggarwal and coworkers of the University of Bristol, in England, have developed a chiral sulfide that gets around both problems (J. Am. Chem. Soc., DOI: 10.1021/ja9100276). By heating elemental sulfur with limonene in the presence of γ-terpinene, they produce isothiocineole, a chiral sulfide that costs less than $1.00 per gram to make. Aggarwal’s team found isothiocineole exhibits outstanding selectivities in sulfur ylide-mediated asymmetric epoxidations and aziridinations. The researchers simply convert the sulfide to a benzylic or allylic sulfonium salt and react it with aldehydes or imines to produce epoxides or aziridines, respectively, with “perfect enantioselectivities and the highest diastereoselectivities reported to date,” the researchers say. The isothiocineole, they write, “should change sulfur ylide-mediated epoxidation into a scalable, mainstream practical method.”


This article has been sent to the following recipient:

Chemistry matters. Join us to get the news you need.