Nucleophilic aromatic substitution using Et3SiH/cat. t-Bu-P4 as a system for nucleophile activation
作者:Masahiro Ueno、Misato Yonemoto、Masahiro Hashimoto、Andrew E. H. Wheatley、Hiroshi Naka、Yoshinori Kondo
DOI:10.1039/b700140a
日期:——
A novel type of deprotonative arylation of nucleophiles was conducted using Et3SiH/cat. t-Bu-P4 and the powerful SNAr reactions of aryl fluorides were accomplished using alcohols and malonates as nucleophiles.
A selective and efficient synthesis of t-butyl 3-alkyl-N-hydroxy-oxindole-3-carboxylates from di-t-butyl 2-nitrophenylmalonates is described. A tandem reduction-cyclization approach involving reduction of di-t-butyl 2-methyl-(2-nitrophenyl)malonate to di-t-butyl 2-(2-(hydroxyamino)phenyl)-2-methylmalonate followed by accelerated cyclization reaction using a combination of Rh/C and hydrazine monohydrate smoothly and selectively afforded the N-hydroxy-oxindole scaffold. This methodology was successfully applied to gram-scale-synthesis of the t-butyl N-hydroxy-3-methyl-oxindole-3-carboxylate 1 without silica gel column chromatographic separation step.