Dioxygenation conjugated dienes

In 1990, Triantaphylidds and coworkers reported on the preparative enzymatic synthesis of hnoleic acid (135) hydroperoxide 24a using soybean lipoxygenase-1. In this dioxygenation asymmetry is induced by the catalyst, the enzyme. The reaction was later used by Dussault and also by Baba and coworkers as key step in the preparation of more complex peroxides. The enzyme is a non-heme iron dioxygenase which catalyzes the incorporation of dioxygen into polyunsaturated fatty acids to yield E,Z conjugated diene hydroperoxides 24a-d. With this enzymatic method, the hydroperoxide 24a could... 

Catalyst conditions very similar to those employed in Eq. 42 and Scheme 12 were used recently by Lloyd-Jones, Booker-Milburn, and coworkers to achieve Pd-catalyzed diamination of conjugated dienes with urea nucleophiles (Eq. 44) [181], Both dioxygen and BQ were evaluated as oxidants, and BQ proved to be significantly more effective (Eq. 44). The beneficial effect of BQ probably arises from its ability to promote nucleophihc attack on the intermediate Tt-allyl palladiiun complex (see below. Sect. 4.4). This hypothesis is supported by the observation that the oxidative amination of styrene with urea, which does not undergo the second nucleophilic attack, proceeds equally effectively with both O2 and BQ as the oxidant (Eq. 45). 

Scheme 29. Cation radical chain dioxygenation of conjugated dienes.

Lipoxygenase (EC 1.13.11.12) catalyses the stereospecific dioxygenation of polyunsaturated fatty acids containing a l,4-cis,cis-pentadiene system to a pentadienyl radical intermediate which reacts with molecular oxygen to yield ris,trans-conjugated diene hydroperoxides (Wiseman et al. 1988). 

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