Synthesis of Nitrogen-Containing Derivatives of (18 α,19 β)-19-Hydroxy-2,3-secooleanane-2,3,28-trioic Acid 28,19-Lactone.

The object of this study is the interaction of the cyclic anhydride 2 of (18 α,19 β)-19-hydroxy-2,3-secooleanane-2,3,28-trioic acid 28,19-lactone ( 1) with primary and secondary amines. It was shown that the products of steric control (the corresponding 2-amino-2-oxo-3-oic acids=2-amides) were formed solely upon the opening of the anhydride cycle by secondary amines ( Scheme 2), whereas the interaction with primary amines yielded a mixture of isomeric amides ( Scheme 10). In the latter case, the solvent provided a noticeable effect on the reaction selectivity, which was demonstrated in the case of 4-methoxybenzylamine. The interaction between the resulting 3-amides and oxalyl chloride yielded the corresponding cyclic imides, whereas under these conditions, 2-amides formed spiropyrrolidinetriones ( Scheme 4). [ABSTRACT FROM AUTHOR]