The cleavage of 1-amino-2'-nitrobenzylphosphonates in a basic medium. Formation of the 3-amino-2,1-benzisoxazole derivatives

Treatment of 1-amino-2'-nitrobenzylphosphonic acids with aqueous sodium hydroxide caused a C-P bond cleavage, with formation of 3-amino-2,1-benzisoxazole derivatives (3). The leaving phosphorus moiety was identified here as phosphoric acid. In the case of basic hydrolysis of corresponding esters, new cyclic phosphorus compounds (derivatives of benzoxazaphosphorin-3,1,2 P-V-one-2) were obtained. The cyclic products were formed as a result of the subsequent reaction of anthranil derivatives with leaving phosphorus fragment, presumably metaphosphate. These benzoxazaphosphorins (compounds 4) were converted by means of aqueous hydrochloric acid to 3-amino-2,1-benzisoxazole derivatives. (C) 1997 Elsevier Science Ltd.