The laccase-catalyzed oxidation of a series of substituted 4-hydroxy-chalcones has been investigated. The main isolated dimeric products were, as expected, racemic mixtures of trans-2,3dihydrobenzofuran derivatives, always co-eluted with an additional isomeric dimer with an open structure. The two enantiomers, as well as the coeluted dimeric isomer could be isolated by semipreparative HPLC with a chiral column and were fully characterized. Scheme 1. Laccase-catalyzed dimerization of substituted phenols. of chalcones 1 a-1 c and 2 a-2 d. UPDATES asc.wiley-vch.de Scheme 2. Synthesis

The bio-oxidation of a series of aromatic amines catalyzed by T. versicolor laccase has been investigated exploiting either commercially available nitrogenous substrates [(E)-4-vinyl aniline and diphenyl amine] or ad hoc synthetized ones [(E)-4-styrylaniline, (E)-4-(prop-1-en-1-yl)aniline and (E)-4-(((4-methoxyphenyl)imino)methyl)phenol]. At variance to their phenolic equivalents, the investigated aromatic amines were not converted into the expected cyclic dimeric structures under T. versicolor catalysis. The formation of complex oligomeric/polymeric or decomposition by-products was mainly observed, with the exception of the isolation of two interesting but unexpected chemical skeletons. Specifically, the biooxidation of diphenylamine resulted in an oxygenated quinone-like product, while, to our surprise, in the presence of T. versicolor laccase (E)-4-vinyl aniline was converted into a 1,2-substited cyclobutane ring. To the best of our knowledge, this is the first example of an enzymatically triggered [2 + 2] olefin cycloaddition. Possible reaction mechanisms to explain the formation of these products are also reported.