Thromboxanes, from arachidonic hydroperoxides

Thiophene, dioxirane oxidation, 1156 Thiourea, dialkyl peroxide synthesis, 706 1,4-Thioxane, oxidation, 805-6 Thiyl radicals, triplet oxygen domino reactions, 221-3, 224, 225, 226 THPO (1,2,3,4-tetrahydronaphthyl hydroperoxide), 331-2 Thromboxanes, from arachidonic hydroperoxides, 612... 

The more recently discovered leukotrienes result from arachidonic acid via the 5-hydroperoxide and the 5,6-epoxide (Leukotriene A4, LTA4). The leukotrienes contain a conjugated triene unit within a total of three (from 20 3, n—9), four (from 20 4, n—6), or five (from 20 5, n—3) double bonds. This total unsaturation is indicated by the numerical subscript. While the 8,11,14-triene unit provides the necessary unsaturation for prostaglandins and thromboxanes the 5,8,11-triene unit is required for leukotrienes. The various LTB, LTC, LTD and LTE compounds show a range of pharmacological activities of which the most widely studied is their relation to asthma arising from their bronchoconstricting effect. 

As the first isolable intermediate in the bioconversion of arachidonic acid into prostaglandins and thromboxanes (Eq. 3), PGG2 is a bicyclic peroxide of immense biological importance. It is difficult to obtain pure from natural sources and the presence of the 15-hydroperoxide group adds a further dimension of chemical lability to that associated with the 9,11-peroxide bridge. The chemical synthesis of PGG2 is thus a landmark in prostaglandin chemistry. It also represents a pinnacle of success for the silver-salt route to bicyclic peroxides. 

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