An expedient synthesis of 3-acyltetramic acids of the melophlin family from α-aminoesters and immobilized Ph3PCCO
Abstract The naturally occurring 3-acyltetramic acids (3-acylpyrrolidine-2,4-diones) melophlin A, B, C and G were prepared in few steps from α-aminoesters or their hydrochlorides by cyclization with Ph 3 PCCO under mild conditions. The employment of immobilized, polystyrene-bound ylide greatly simplifies the removal of by-product Ph 3 PO and of other impurities. Various 3-acylation methods were assessed.
This paper deals with the behaviour of hydrolyse d Polyacrylamide solutions in the presence of chromium III. First, using potentiometry and spectroscopy, we study the complexation between chromium III and sodium acetate used as a low molecular weight model for the polymer. Then the same methods are applied to investigate the polymer—Cr(III) complexation and the results are discussed in conjunction with the nature of the physical states of the systems. Finally, we perform rheological measurements in the sol—gel transition regime in a range where the number of crosslinking points can be calculated unambiguously.