New 4-methoxybenzoyl derivatives from the ascidian Polycarpa aurata.

From the hydrophilic extract of the ascidian Polycarpa aurata three new compounds, N-(4-methoxybenzoyl)-N'-methylguanidine (1), butyl 2-(4-methoxyphenyl)-2-oxoacetate (2), and 2-(4-methoxyphenyl)-N-methyl-2-oxoacetamide (3), together with the known compounds methyl 2-(4-methoxyphenyl)-2-oxoacetate (4) and 4-methoxybenzoic acid were isolated. The structures of all isolates were determined from their spectroscopic data (NMR, MS, IR, UV).