The first example of the generation of azomethine ylides from a fluorocarbene: 1,3-cyclization and 1,3-dipolar cycloaddition

A simple route to side-chain fluorinated β-lactams from ring-fluorinated aziridines

“…2-Fluoroaziridines 1a-c were synthesized from N-benzyl-, N-methoxycarbonylmethyl-and N-methyl-imines of benzophenone and monofluorocarbene (generated by the reduction of CHFBr 2 with active lead according to the published procedure [31]). Diphenylketene 3a was prepared according to the known procedure [32] and oxy-substituted ketenes 3b,c were generated in situ from the appropriate acid chloride and triethylamine.…”

“…Recently we have demonstrated that some fluorinated imines are accessible by isomerization of 2-fluoroaziridines, which in turn can be prepared by cycloaddition of monofluorocarbenes to imines [30,31]. In the present study reactions of diphenylketene and ketenes, bearing oxy-groups, with a-fluoroimines generated from 2-fluoroaziridines were examined as a potential route to side-chain fluorinated b-lactams (Scheme 2).…”

Recent progress in the use of fluoroorganic compounds in pericyclic reactions

“…By the same method, monofluorinated azomethine ylides can be generated from imines and dibromofluoromethane. 99,100 These species can be trapped by electron-poor alkenes or alkynes in a [3þ2] cycloaddition, yielding pyrroles or their derivatives after in situ elimination of HF.…”

Formation and reactivity of gem-difluoro-substituted pyridinium ylides: Experimental and DFT investigation

“…The reversibility of the formation of gemdifluorosubstituted iminium ylides is the origin of some peculiarities of its reactivity. In particular they do not cyclize to aziridines in contrast to monofluoro- [7] and gem-dichloro-substituted analogues [8].…”