Anethole epoxide

Fig. 10.27. Mechanistic and stereochemical aspects of the hydration of trans-(R,K)-anethole epoxide in the absence (Reactions a and b) and presence of epoxide hydrolase (Reaction c) [178][179]. The ratio of Reaction a to bis ca. 4 1 in acid- and base-catalyzed hydration to yield the threo- and erythro-diols, respectively. The enzymatic Reaction c also yields preferentially the erythro-diol.

The initial steps in the degradation of 2 -methyl-4-methoxystyrene (tran -anethole) by a strain of Arthrobacter aurescens are comparable to those already noted, except that the epoxide is hydrolyzed to a diol to produce 4-methoxybenzoate (Shimoni et al. 2002). 

In closely related studies, the acid-catalyzed hydrolyses of cis- and trans-jl-mc-thylstyrene oxides (42a and 44a)51 52 and of cis- and trans-anethole oxides (42b and 44b)53 have been reported (Scheme 12). Reactions of the cis and trans epoxides in... 

Another example of an epoxide isomerization occurring by a similar mechanism is the pH-independent reaction of cts-anethole oxide 121, which yields (n-methoxy-phenyl)acetone 125 along with threo and erythro l-(p-methoxyphenyl)-l,2-pro-panediols 126.107 During the course of the reaction, trans-anethole oxide (124) builds up to a level that is detected by JH NMR (Scheme 35). The mechanism for this reaction involves benzylic C-0 bond breaking, rotation about the Cx-Cp bond via zwitterionic structures 122 and 123, and epoxide ring closure to form trans-anethole... 

Tetraphenyiporphine-sensitized photooxygenation of frans-anethole (1 b) in CCi4 afforded a 1,2-dioxene (2 b) and an a-diketo epoxide (4b) along with a dihydropyranoi (3 b), 2-hydroxy-4-methoxybenzaldehyde (5 b), 4-methoxyhenz-aidehyde (6 b), 4- ethoxyphenyi vinyi ketone (7b) and frans-anethoie Different product distributions were obtained for 3-methyistyrene and isosafroi. 

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