Efficient Synthesis of t-Butyl 3-Alkyl-N-hydroxyoxindole-3-carboxylates from Di-t-butyl 2-nitrophenylmalonates
作者:Takaaki Sumiyoshi、Yu-suke Yamai、Kyoji Ishida、Itaru Natsutani、Shinichi Uesato、Yasuo Nagaoka
DOI:10.3987/com-18-s(t)82
日期:——
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.