Of tetramic acid-containing

The variety of tetramic acid-containing natural products is remarkable, the area having been reviewed recently [130]. These compounds have attracted a great deal of interest, due mainly to their biological activity as potent antibiotics, because of their antiviral and antiulcerative properties, cytotoxicity and mycotoxicity, their inhibition of tumors as well as. fungicidal action. Other members are responsible for the pigmentation of certain molds and sponges. 

Some phosphonates, e.g., (165), derived from tetramic acids have been prepared and shown to undergo normal olefination with ketones in work ultimately aimed at the synthesis of tetramic acid-containing natural products. A general method for the synthesis of 3-enoyl and 3-dienoyl tetramic acids, involving olefination with the phosphonate (166), has been reported. ... 

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