Catechols catalytic oxidative cleavage

Catalytic oxidative cleavage of catechols 6.3.1. Base catalyzed oxidations... 

Interest in catechol as a substrate for oxidation stems from the discovery of its oxidative ring cleavage by the first oxygenase enzyme pyrocatechase. 3,5-Di-t-butylcatechol (3,5-DTBC) has been widely used as a substrate in various catalytic oxygenations (dehydrogenations). Most of the mechanistic information now available on various catalyst systems has been obtained from studies on 3,5-DTBC oxidation. 

Nakanishi et al obtained a purified 2,3-CTD from an aniline-assimilating bacterium, Pseudomonas sp. FK-8-2 [136]. The relative activity is different from that by Nozaki et al. [133] as shown by the activity order (relative activity) R = 3-Me- (1.1) > H (1) > 4-Me- (0.53) 4-Cl (0.03) > 3-F (0.02) 4-COOH (0). Kohler et al. studied the metapyrocatechase activity of the partially purified enzyme from a mutant Pseudomonas sp. strain HBPl Prep and found a specifically high activity to 2,3-dihydroxybiphenyl [137]. The order of the activity is 2,3-dihydroxybiphenyl (62.2) 3-propyl (3.24) > 3-Me- (1.59) > H- (1.0) 4-Me-catechol (0.08). Catalytic activity of modified enzymes by molecular cloning has been also studied by Kobatake et al. [138], Keil [139], Chang et al. [140, 141], Nishihara et al. [142], and Cerdan et al. [143]. Cerdan et al. reported that 2,3-CTD encoded by TOL Plasmid pWWO of Pseudomonas putida catalyzes ring cleavage of catechol, 3-Me- and 4-Me-catechols but shows only weak activity toward 4-Et-catechol. Two mutants of 2,3-CTD are able to oxidize 4-Et-catechol and another mutant exhibits only weak activity toward 3-Me-catechol but retains the ability to cleave catechol and 4-Me-catechol [143]. 

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