112403-72-2Relevant academic research and scientific papers
Electrophilic Aromatic Substitution with N-Methoxy-N-acylnitrenium Ions Generated from N-Chloro-N-methoxyamides: Syntheses of Nitrogen Heterocyclic Compounds Bearing a N-Methoxyamide Group
Kawase, Masami,Kitamura, Takahiro,Kikugawa, Yasuo
, p. 3394 - 3403 (2007/10/02)
N-Methoxy-N-acylnitrenium ions (II), generated by treatment of N-chloro-N-methoxyamides with silver carbonate in trifluoroacetic acid, react with arenes to give N-aryl-N-methoxyamides in good yields.In the case of the intramolecular cyclization of N-chloro-N-methoxy-2-phenylacetamides, the mode of cyclization is highly dependent on the nature of ortho or para substituent groups.Nitrenium ions II can primarily attack three positions (C-1, C-2, and C-6) of a phenyl ring.Normally II attack C-6.On the other hand, when the ortho position was occupied with a substituent group, II attacked both C-2 and C-6, in the former case followed by a 1,2-substituent migration, which was proved by a deuterium labeling experiment.Especially, when a methoxy group is substituted on ortho or para position, II attack C-1 due to the effect of the electron-releasing methoxy group to give spiro dienone compounds 39.A general discussion of the utility and mechanistic details of these reactions is presented.
N-ALKOXY-N-ACYLNITRENIUM IONS IN INTRAMOLECULAR AROMATIC ADDITION REACTIONS
Glover, Stephen A.,Goosen, Andre,McCleland, Cedric W.,Schoonraad, Johan L.
, p. 2577 - 2592 (2007/10/02)
N-alkoxy-N-acylnitrenium ions are generated by treatment of N-alkoxy-N-chloroamides with silver ions in ethereal solvents.These intermediates readily cyclise onto aromatic nuclei on alkoxy side-chains to give benzoxazines and benzoxazepines and on the acyl side-chains to give γ, δ and ε benzolactams.Spirane products are formed by ipso addition when a 4-methoxy substituent is present on the side-chain aromatic rings.The yields and regioselectivities of these reactions have been ascribed to different transition structures for cyclisation onto the acyl and alkoxy side-chains which involve respectively an exocyclic and endocyclic N-O ?-bond.Evidence for this exeptionally high ?-bond character has been obtained from MNDO calculations which predict a ?-bond order of 0.9 and a rotational barrier of 29.7 kcalmol-1
