Synthesis of aziridines
The use of N-Boc-O-tosylhydroxylamine (TsONHBoc) and N-methyl-O-tosylhydroxylamine (TsONHMe) as aminating agents enables a metal and additive-free stereospecific direct N-H and N-Me aziridination of inactivated olefins in hexafluoroisopropanol (HFIP). TsONHBoc, which generates the free aminating agent in situ, offers low cost, easy access, and stability (non-explosiveness).
J. L. Jat, D. Chandra, P. Kumar, V. Singh, B. Tiwari, Synthesis, 2022, 54, 4513-4520.
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 highly efficient Rh(II)-catalyzed direct preparation of unactivated aziridines from olefins relies on O-(sulfonyl)hydroxylamines as the aminating agents. The reactions proceed with high stereospecificity.
S. Sabir, C. B. Pandey, A. K. Yadav, B. Tiwari, J. L. Jat, J. Org. Chem., 2018, 83, 12255-12260.
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.
Styrenes reacted with sulfonamide in the presence of potassium carbonate and iodine in CHCl3 under visible light irradiation to produce the corresponding aziridines in good yields.
K. Matsuzawa, Y. Nagasawa, E. Yamaguchi, N. Tada, A. Itoh, Synthesis, 2016, 48, 2845-2850.
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.
An efficient electrocatalytic aziridination of alkenes provides a structurally broad range of aziridines using an undivided cell operated at constant current and mediated by a catalytic quantity of n-Bu4NI. The electrocatalytic reaction also proceeded in the absence of additional conducting salt.
J. Chen, W.-Q. Yan, C. M. Lam, C.-C. Zeng, L.-M. Hu, R. D. Little, Org. Lett., 2015, 17, 986-989.