Synthesis of aziridines
A mild, efficient, and selective aziridination of olefins with p-toluenesulfonamide catalyzed by dirhodium(II) caprolactamate is described. Aziridine formation occurs through aminobromination and subsequent base-induced ring closure.
A. J. Catino, J. M. Nichols, R. E. Forslund, M. P. Doyle, Org. Lett., 2005, 7, 2787-2790.
A metal-free catalytic aziridination of styrene derivatives with N-tosyliminophenyliodinane (PhI=NTs) is promoted by a combination of I2 and tetrabutylammonium iodide (TBAI). TBAI3 as highly efficient catalyst as well as N,N-diiodotosylamide as actual aziridination reagent are generated in situ.
K. Kiyokawa, T. Kosaka, S. Minataka, Org. Lett., 2013, 15, 4858-4861.
N-N ylides for the aziridination of a range of enone systems can be prepared by in situ amination of a tertiary amine. The amine may be used sub-stoichiometrically, and promising levels of enantioselectivity are observed with quinine as promoter.
A. Armstrong, C. A. Baxter, S. G. Lamont, A. R. Pape, R. Wincewicz, Org. Lett., 2007, 9, 351-353.
Aziridination of vinyl ketones using SESN3 in the presence of a Ru(CO)-salen complex provides synthetically useful enantiopure aziridinyl ketones. A formal asymmetric synthesis of (+)-PD 128907 was achieved in an eight-step sequence via aziridination.
Y. Fukunaga, T. Uchida, Y. Ito, K. Matsumoto, T. Katsuki, Org. Lett., 2012, 14, 4658-4661.
An efficient and practical aminohalogenation and in situ intramolecular SN2 substitution of α,β-unsaturated esters and ketones gave N-p-tosyl-aziridine-2-ketones and carboxylates in moderate to good yields and excellent anti stereoselectivity. Triethylamine was found to be an effective base for the in situ cyclization for most substrates.
D. Chen, C. Timmons, L. Guo, X. Xu, G. Li, Synthesis, 2004, 2479-2484.
A gold(I) compound, supported by 4,4',4' '-tri-tert-butyl-2,2':6',2' '-terpyridine (tBu3tpy) as the ligand, efficiently catalyzes olefin aziridination with the use of the commercially available oxidant PhI(OAc)2 and sulfonamides.
Z. Li, X. Ding, C. He, J. Org. Chem., 2006, 71, 5876-5880.
Complementary to existing routes, the Lewis acid catalyzed reactions of phenyldiazomethane with α-imino esters selectively produce cis-aziridine-2-carboxylates without competitive formation of enamino ester or carbene dimer byproducts.
A. Mazumdar, Z. Xue, M. F. Mayer, Synlett, 2007, 2025-2028.
An electrochemical aziridination process is described that delivers a nitrene functionality to olefins from N-aminophthalimide. Remarkably, both electron-rich and electron-poor olefins are converted to aziridines with high efficiency. The selectivity is discussed.
T. Siu, A. K. Yudin, J. Am. Chem. Soc., 2002, 124, 530-531.
A straightforward synthesis of aziridines is reported from electron-rich azides, electron-deficient olefins, and triflic acid in cold acetonitrile. Ester substrates bearing a nucleophilic carbonyl give products of an olefin aminohydroxylation.
J. M. Mahoney, C. R. Smith, J. N. Johnston, J. Am. Chem. Soc., 2005, 127, 1354-1355.