Synthesis of Novel Organogermanium Sesquioxides and Reactivities of 3-(Trichlorogermyl)propanoic Acid

During the past two decades, carboxyethylgermanium sesquioxide Ge-132O₃(GeCH₂CH₂COOH)₂] and its derivatives have attracted considerable attention because these organogermanium sesquioxides exhibited anticancer activities1,2]. In 1993, Kurono et al. have synthesized phosphonoethylgermanium sesquioxideO_3/2GeCH₂CH₂PO(OH)₂], which possesses higher antitumor activity than Ge-1323]. Encouraged by these promising results, we developed the idea that the incorporation of a germanium residue into α-aminophosphonic acids and their derivatives, which have antibacteria and antitumor activities4,5], would enhance their antitumor activities to a significant degree, while their toxicity would be reduced at the same time. Therefore, we designed and synthesized a series of novel organogermanium sesquioxides containing α-aminophosphonate groups by the hydrolysis of O,O-diphenyl N-trichlorogermyl propiono-α-aminophosphonates.