Metal- and Oxidant-Free Modular Approach To Access <i>N</i>-Alkoxy Oxindoles via Aryne Annulation
作者:Ritesh Singh、Kommu Nagesh、Doddapaneni Yugandhar、A. V. G. Prasanthi
DOI:10.1021/acs.orglett.8b01972
日期:2018.8.17
An unprecedented metal- and oxidant-free (intermolecular) approach to access N-alkoxy oxindoles via [3 + 2] cycloadition of in situ generated electrophilic species viz. aryne and (putative) aza-oxyallyl cation is reported. This approach is amenable to both C3-unsubstituted as well as C3-substituted oxindoles. A one-pot manipulation further makes this reaction highly practical. The versatility of this approach was demonstrated through valuable synthetic transformations.
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.
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