Stereoselective Lewis Acid Mediated (3+2) Cycloadditions of N-H- and N-Sulfonylaziridines with Heterocumulenes
Alkyl and aryl isothiocyanates and carbodiimides are effective substrates in (3+2) cycloadditions with N-sulfonyl-2-substituted aziridines and 2-phenylaziridine for the synthesis of iminothiazolidines and iminoimidazolidines. Additionally, the stereoselective (3+2) cycloaddition of N-H- and N-sulfonylaziridines with isothiocyanates can be accomplished, allowing for the synthesis of highly enantioenriched iminothiazolidines. Evidence for an intimate ion-pair mechanism is presented herein in the context of these chemo-, regio-, and diastereoselective transformations. The demonstrated ability to remove the sulfonyl group from the heterocyclic products displays the utility of these compounds for further derivatization and application.
Additional Information© 2013 Wiley-VCH Verlag GmbH & Co. Received: September 21, 2013. Article first published online: 6 Mar. 2014. The authors wish to thank NIH-NIGMS (R01M080269-01), Amgen, and Caltech for financial support. R.A.C. gratefully acknowledges the support of this work provided by a fellowship from the National Cancer Institute of the National Institutes of Health under Award Number F31A174359. A.F.G.G. thanks the Natural Sciences and Engineering Research Council (NSERC) of Canada for a PGS D scholarship. L. Henling (Caltech) and Dr. M. Takase (Caltech) are gratefully acknowledged for X-ray crystallographic structural determination. The Bruker KAPPA APEXII X-ray diffractometer was purchased via an NSF CRIF:MU award to the California Institute of Technology, CHE-0639094.
Accepted Version - nihms577378.pdf
Supplemental Material - chem_201303699_sm_miscellaneous_information.pdf