Laccase-catalyzed reaction of 3-tert-butyl-1H-pyrazol-5(4H)-one with substituted catechols using air as an oxidant

Laccase-mediated multi-step homo- and heteromolecular reactions of ortho -dihydroxylated aromatic compounds and mono- or diaminated substances resulting in C C, C O and C N bonds

“…In contrast to the homomolecular reactions described by Nicotra et al [38], Kordon et al [39] and in our study, the formation of heteroaromatic five-membered rings resulting from heteromolecular reactions of ortho-hydroquinones have been repeatedly studied [17][18][19][20][21][22].…”

“…Different types of heterocycles may be formed during laccase-catalyzed reactions. In this way five-membered rings such as benzofurans [15,16], dibenzofurans [17][18][19][20][21], thiazoles [22] as well as six-membered rings such as phenoxazinone chromophores [23][24][25] have been synthesized.…”

Enhanced Biocatalytic Performance of Bacterial Laccase from Streptomyces sviceus: Application in the Michael Addition Sequence Towards 3‐Arylated 4‐Oxochromanes

“…Nevertheless, the outcome was surprising as laccase-catalysed arylations with 23 were described previously to provide coupling exclusively in the 4'-position. [19] Clearly, the choice of nucleophile also influences the outcome of the regioselectivity significantly.…”

Cost-effective electrosynthesis of a series of edaravones through an electrochemical-assisted domino heteroannulation and paired electrochemical process

“…Also notably, the existence of a methyl or methoxy group at the C-3 position of 1b or 1c and a methyl, tert-butyl or nitro group at the C-4 position of 1d, 1e, and 1g may have subtle effects on the reactivity of their relevant ortho-bezoquinones and would probably cause these Michael-type acceptors (2b, 2c, 2d, 2e, and 2g Scheme 1) to be attacked by I from the C-3, C-4, C-5, or C-6 positions. Because methyl, methoxy, and tert-butyl groups are electron-donating substituents, it seems that ortho-benzoquinones 2b, 2c, 2d, and 2e are more electropositive at C-5 position and therefore the 1,4-addition exclusively occurs at the more electrophilic carbon atom of the corresponding ortho-benzoquinones [11,29]. So ortho-benzoquinones 2b, 2c, 2d, and 2e can be selectively attacked in all probability only at the C-5 position by I leading to the formation of intermediates 3b and 3c and final products 3d and 3e (Scheme 1), respectively.…”

“…As depicted in Scheme 1, similar to that of 3a, further oxidation of these intermediates (3b, 3c) is followed by an intramolecular Michael-type reaction, which leads to the final products. Also ortho-benzoquinones 2e is more electropositive at C-5 position and therefore the 1,4-addition exclusively occurs at the more electrophilic carbon atom of the corresponding ortho-benzoquinones [11,29], thus leading to the formation of final product 3g.…”