91523-38-5Relevant 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
