Epoxides and aziridines - a mini review

Abstract

Three-membered heterocyclic rings offer an uncommon combination of reactivity, synthetic flexibility, and atom economy. This mini review surveys a selection of the most recent advances amongst epoxides and aziridines. Emphasis is given to novel synthetic methods and new insights into existing methodologies for the selective construction and controlled reaction of the title compounds reported in the past year's literature. While not the exclusive focus of this minireview, well-represented themes in the literature include asymmetric techniques and environmentally compatible reagents.

Recent applications of aziridine ring expansion reactions in heterocyclic synthesis

“…57 The reaction was significantly accelerated by using an electron-poor sulfonamide (nosyl instead of tosyl) and modestly accelerated when electron-rich olefins were employed, compared to electron-poor olefins. Moreover, a M(hfacac) 2 additive could accelerate the reaction, with Zn(hfacac) 2 …”

“…The reaction of an optically active aziridine 110a with a series of N-methylanilines 164 afforded imidazolidines 165 with excellent optical purity (ee >99%) (Scheme 50). The plausible mechanism for the formation of products involves coordination of Cu(OTf) 2 …”

“…More recently, Xing and coworkers have reported a Lewis acid (BF 3 .OEt 2 )-catalyzed three-component reaction of arenes, aldehydes, and N-tosylsubstituted 2-arylaziridines forming cis-1,4-disubstituted tetrahydroisoquinolines in moderate yields. 120 The reaction proceeds through an iminium ion, generated from the reaction of aldehydes with amines [ArCH(Ar)CH 2 NHTs] that formed after the Lewis-acid catalyzed ring-opening of aziridines. .…”

“…The synthesis and reactivity of aziridines have been reviewed from time to time. 2,3 Some review articles focusing on specific type of aziridines such as aziridine-2-carboxylates, 4 2-haloaziridines, 5 2-methyleneaziridines, 6 and 2-vinylaziridines 7,8 have been published. This review paper aims to describe recent applications (2008 to early 2017) of aziridines, whether activated or non-activated, in synthesis of other heterocyclic frameworks by aziridine ring expansion.…”

Modified Vegetable Oil Based Additives as a Future Polymeric Material—Review

“…Several attempts have been made to improve their oxidative stability such as transesterification of trime- thylopropane and rapeseed oil methyl ester [72]; selective hydrogenation of polyunsaturated C=C bonds of fatty acid chains [73] and conversion of C=C bonds to oxirane ring via epoxidation [74] [75]. Among these, epoxidation received special attraction because it opened up a wide range of feasible reactions that can be carried out under moderate reaction conditions due to the high reactivity and functionality of the oxirane ring [76]. For instance, the epoxides can react with different nucleophiles to produce mono-alcohols, diols, alkoxyalcohols, hydroxyesters, N-hydroxyalkylamides, mercaptoalcohols, aminoalcohols, hydroxynitriles, etc.…”