title: Analogues of poison ivy urushiol. Synthesis and biological activity of disubstituted n-alkylbenzenes.
abstract: The total synthesis of different isomers and analogues of poison ivy urushiol is described. These include the positional isomers 1-5 and the nitrogen-containing analogues 6 and 8 and their mesylamino derivatives 7 and 9. 3,4-Dimethoxybenzaldehyde, m-dimethoxybenzene, resorcinol, and p-dimethoxybenzene were used as starting materials for compounds 1, 2, 3, and 4, respectively. Compound 5 is prepared by catalytic hydrogenation of bilobol isolated from Ginkgo biloba. Compounds 6 and 7 were prepared from anacardic acid as the starting material while compounds 8 and 9 were prepared from phenol as the starting material. Compounds 1-9 were tested for their ability to cross-react with poison ivy urushiol in sensitized guinea pigs. Compounds 6 and 8 were reactive at the 10-microgram dose level when applied topically, while compound 1 was a skin irritant at that dose. On the other hand, compounds 2-5, 7, and 9 showed no cross-reactivity up to the 30-micrograms dose level. Structural requirements for cross allergenicity are discussed.
mesh_terms: D000818:Animals; D002396:Catechols / Q000138:chemical synthesis* / Q000627:therapeutic use; D003429:Cross Reactions; D011040:Dermatitis, Toxicodendron / Q000517:prevention & control; D006168:Guinea Pigs; D007536:Isomerism; D010947:Plants, Toxic; D013329:Structure-Activity Relationship; D012251:Toxicodendron
chemical_list: D002396:Catechols; C005297:3-pentadecacatechol; C003747:urushiol