646995-90-6Relevant academic research and scientific papers
A Concise Synthesis of Sterically Hindered 3-Amino-2-Oxindoles
O'Connor, Stephen J.,Liu, Zheng
, p. 2135 - 2138 (2007/10/03)
A new method for the synthesis of 3-alkyl-3-amino-2-oxindoles is reported. These compounds are prepared in a 3-step procedure using a base-mediated nucleophilic addition of benzylidene-imine protected α-aminoesters to 2-nitrofluorobenzene as the key step. The process provides a variety of 3-alkyl-3-amino-2-oxindole analogs in yields of 1-24%. Yields are highest with alanine, phenylalanine and 2-pyridylalanine as the amino acid starting materials, while 3-pyridylalanine and O-methyltyrosine are less efficiently arylated. Sterically hindered amino acids such as valine and phenylglycine are for all practical purposes, not substrates for the key nucleophilic substitution reaction. The resulting 3-alkyl-3-amino-2-oxindoles are important intermediates for the preparation of drug-like substances. The conversion of alanine ethyl ester to 3-amino-3-methyl-2-oxindole is described.
