Synthesis of aziridines
The reaction of N-tosyl imines with in situ generated iodomethyllithium, with a simple and rapid experimental protocol, allows an efficient and general synthesis of aziridines. A reaction of a chiral aldimine derived from phenylalaninal proceeded with high diastereoselectivity. A mechanism to explain this novel reaction is proposed.
J. M. Concellón, H. Rodríguez-Solla, C. Simal, Org. Lett., 2008, 10, 4457-4460.
Aldimines (generated in situ from aldehydes and amines) react readily with ethyl diazoacetate in the presence of 2 mol% of Bi(OTf)3 in [bmim]PF6 to produce the corresponding aryl aziridine carboxylates in high yields with excellent cis-diastereoselectivity.
J. S. Yaday, B. V. S. Reddy, P. N. Reddy, M. Shesha Rao, Synthesis, 2003, 1387-1389.
Montmorillonite K-10 as solid acid catalyzes a stereoselective reaction of imines with ethyl diazoacetate to yield cis-aziridines. The reactions proceeded readily at room temperature in short reaction times, providing the products in very good yields and exclusive selectivity.
D. Borkin, A. Carlson, B. Török, Synlett, 2010, 745-748.
The tertiary amine DABCO catalyzes the reaction of imines with phenacyl bromide derivatives to afford functionalized aziridines in high yields and stereoselectivities in a one-pot process - including the formation of ylides and their precursors.
L. D. S. Yadav, R. Kapoor, Garima, Synlett, 2009, 3123-3126.
A mild, convenient protocol for the synthesis of cis-aziridines employs a catalytic amount of Brřnsted acid. Diazo compound decomposition via alkylation or homocoupling upon exposure to a proton source is slow relative to [2 + 1] annulation in the presence of a Schiff base.
A. L. Williams, J. N. Johnston, J. Am. Chem. Soc., 2004, 126, 1612-1613.
The reaction of trimethylsilyldiazomethane with N-sulfonyl (Ts and SES) imines provides aziridines in good yields and high cis stereoselectivities. The silyl group can be substituted by treatment with a fluoride source and electrophiles again with high selectivity. In addition, complete regioselectivity is observed in ring opening reactions of these aziridines with nucleophiles.
V. K. Aggarwal, M. Ferrara, Org. Lett., 2000, 2, 4107-4110.
Adducts derived from P(NMe2)3 and α-ketoesters are effectively intercepted by N-sulfonyl imines, affording a range of aziridine-2-carboxylates. The diastereoselectivity of this aziridination depends on steric hindrance from substituents on the substrates.
J. Jiang, H. Liu, C.-D. Lu, Y.-J. Xu, J. Org. Chem., 2017, 82, 811-818.
A clean and fast aziridination of diazoacetamides with N-Boc-imines, as well as N-Cbz-imines, catalyzed by a chiral phosphoric acid in DCM at room temperature achieves excellent yields, diastereoselectivities, chemoselectivities, and enantioselectivities.
X. Zeng, X. Zeng, Z. Xu, M. Lu, G. Zhoung, Org. Lett., 2009, 11, 3036-3039.