Aziridine ring opening alkylative

Thiocyanate ion was found to open iV-tosylaziridines in the presence of catalytic amounts of LiC104 in acetonitrile.48 When a benzyl substituent was present, the. S N reaction occurred at the benzyl carbon of the aziridine ring but at the less-substituted carbon when the substituent on the aziridine ring was alkyl. Every substitution product had a trans stereochemistry. 

Lithium dibutylcuprate Alkylative aziridine ring opening... 

Recently, in 2008, Dixon and co-workers [96] developed highly efficient enantioselective a-alkylation of cyclic p-ketoesters with o-(trifiuoromethane)benzene-sulfonyl aziridine 39 under phase-transfer catalysis with (9-adamantoyl derivative LII (up to 85% yield and 97% ee). Moreover, the corresponding products 40 were obtained with high diastereoselectivity when PTC aziridine ring-opening of single enantiomeric aziridines was performed. In this work, also formation of diastereomerically pure tricyclic compounds via one-pot alkylation/desulfonation/ cyclization sequence was described. 

Certain reagents promote ring opening and subsequent cyclization to give other heterocycles. For example, di-tert-butyl dicarbonate induces the stereoselective ring transformation of N-alkyl aziridines 159 into oxazolidin-2-ones 160 <96TET2097>. 

Thioacetals eliminate to vinylsulfides in the presence of CuOTf (Scheme 46).192 Cu1 and Cu11 triflates are mild Lewis acids for Friedel-Crafts acylation and alkylation reactions. CuOTf effectively catalyzes the reaction of anisole with selenoesters.193,194 Copper(II) sulfate promotes epoxide ring opening reactions in the presence of pyridine,195 with retention of configuration being observed. Cu(OTf)2 is a catalyst for the ring opening of aziridine by aniline.196... 

Ring opening of meso aziridines has also been investigated. Jacobsen and coworkers found that tridentate Schiff base Cr(III) complex 62 is efficient at inducing good levels of enantioselectivity in the azidolysis of aziridines 60 [Eq. (10.15)]. Alkyl-substituted aziridines were found to work best with the electron-deficient dinitrophenylmethyl providing optimal results ... 

The same regiochemistry is observed when nitroimidazole (48-2, 48-3) acts as a nucleophile in unionized form. Thus, the reaction of a compound with benzoyl-aziridine (49-1) in the presence of boron trifluoride probably involves an initial salt formation with an amide attack by the imidazole results in a ring opening and the formation of the alkylated product (49-2) the free primary amine (49-3) is obtained on basic hydrolysis. Acylation of the primary amine with methyl thiochloroformate gives the corresponding thiourethane, carnidazole (49-4) [52]. 

Triazolines (116), in which there is no free hydrogen on C-4, also thermolyze to aziridines and enamines.67,454 When R is phenyl, regardless of the X substituent, aziridine is the only thermolysis product but when R is alkyl or hetaryl,453 a mixture of aziridine and enamine is obtained, the latter being the predominant product in some cases.67,453 Because enamine formation from the ring-opened diazo isomers does not seem feasible, a diradical intermediate is proposed.67... 

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