Abstract: A series of 2-amino-3'-alkylaminomethyl-4'-hydroxy-6-substituted isoflavones (Ⅱ) were synthesized. The intermediates, methyl 2-methoxy-5-substituted benzoates were prepared by using the technique of phase transfer catalysis and esterification and etherification took place simultaneously. The products (Ⅴ) from Claisen condensation of 2-methoxy-5-substituted benzoates (Ⅲ) with p-methoxybenzeneace-tonitrile (Ⅳ) were demethylated by BBr₃ and cyclized to 2-amino isoflavone derivatives (Ⅵ). The existence of 2-amino group was confirmed by spectroscopic analysis as well as by replacement of amino group with chlorine atom after diazotization in hydrochloric acid. The different alkylaminomethyl groups were introduced by Mannich reaction. The position attacked by Mannich reagents were determined by ¹HNMR. It atttached uniquely at the ortho position of 4'-hydroxy group. Compounds of formula Ⅱ were tested for resistance to hypoxia in mice and IIbb' was shown to have significant effect.