Electrophilic aromatic substitution with N-methoxy-N-acylnitrenium ions generated from N-chloro-N-methoxy amides: syntheses of nitrogen heterocyclic compounds bearing a N-methoxy amide group
N-alkoxy-n-acylnitrenium ions in intramolecular aromatic addition reactions
作者:Stephen A. Glover、Andre Goosen、Cedric V. McClei、Johan L. Schoonraad
DOI:10.1016/s0040-4020(01)81665-3
日期:——
solvents. These intermediates readily cyclise onto aromatic nuclei on alkozy 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 ia present on the side-chain aromatic rings. The yields and regioselectivities of these reactions have been ascribed to different transition structures
Treatment of N-alkoxy-N-chloroarylacetamides with triethylamine in ethanol results in removal of a chlorine atom and introduction of an ethoxy group at the C-2 position of arylacetamides in moderate yields.
New spirolactams of formula (I) having a benzodienone moiety and a azetidinone moiety which are highly stable due to pi interactions. They are useful as UV absorbers and as synthetic intermediates.
Intramolecular Cyclization with Nitrenium Ions Generated from<i>N</i>-Chloro-<i>N</i>-methoxyamides in Neutral Conditions
作者:Yasuo Kikugawa、Masahiro Shimada
DOI:10.1246/cl.1987.1771
日期:1987.9.5
Intramolecular aromatic substitution by a N-chloro-N-methoxyamide group to a suitably situated aromatic ring in the molecule is performed by using anhydrous zinc acetate and nitromethane as solvent to give nitrogen heterocycles in good yield.
Cyclization with Nitrenium Ions Generated from N-Methoxy- or N-Allyloxy-N-chloroamides with Anhydrous Zinc Acetate. Synthesys of N-Hydroxy- and N-Methoxynitrogen Heterocyclic Compounds
Electrophilic intramolecular aromatic substitution with an N-methoxy- or an N-allyloxy-acylnitrenium ion, generated by treatment of an N-methoxy- or an N-allyloxy-N-chloroamide with anhydrous zinc acetate in nitromethane, leads to formation of a nitrogen heterocyclic compound bearing an N-methoxy- or N-allyloxy group. The latter is readily converted to the corresponding N-hydroxy compound by palladium-catalyzed removal of the allyl group.