95207-34-4Relevant academic research and scientific papers
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
N-Alkoxy-N-acylnitrenium Ions as Possible Intermediates in Intramolecular Aromatic Substitution: Novel Formation of N-Acyl-3,4-dihydro-1H-2,1-benzoxazines and N-Acyl-4,5-dihydro-1H,3H-2,1-benzoxazepine
Glover, Stephen A.,Goosen, Andre,McCleland, Cedric W.,Schoonraad, Johan L.
, p. 2255 - 2260 (2007/10/02)
N-Halogeno-N-alkoxyamides undergo intramolecular aromatic substitution by thermal- or Lewis acid-catalysed heterolysis of the nitrogen-halogen bond.N-Acyl-N-alkoxynitrenium ions are likely intermediates.N-Chloro-N-methoxybiphenyl-2-carboxamide (4) yields N-methoxyphenanthridone (11) quantitatively with AgBF4, while O-2-phenylethyl-N-chlorobenzohydroxamate (19) is converted in good yield into N-benzoyl-3,4-dihydro-1H-2,1-benzoxazine (21) with AgBF4, AgClO4, HgO, and Hg(OAc)2.N-Acetyl-3,4-dihydro-1H-2,1-bezoxazine (22) is formed similarly.O-3-Phenylpropyl-N-chlorobenzohydroxamate (23) cyclises to N-benzoyl-4,5-dihydro-1H,3H-2,1-benzoxazepine (24) with AgBF4.
