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. Thujone, a waste by-product of the Canadian forest industry, has been utilized as a starting material to develop a versatile synthetic route to the darnascones (rose oil ketones) and related analogues. The synthetic sequence provides a route to P-cyclocitral ( 4 9 , the latter having been previously converted to P-damascone (2). In addition, thujone-derived intermediates are converted to P-damascenone (48) and to intermediates that can be utilized for the preparation of damascone analogues. In conjunction with the above, an efficient route to safronitrile (42), P-cyclogeranonitrile (43), and P-cyclocitral (45) from 2,6-dimethylcyclohexanone has been developed. In summary, these studies afford an attractive versatile route to these important perfumery materials.

. Can. J. Chem. 67, 1472Chem. 67, (1989. Addition of nitronium ion ipso to halogen occurs on nitration of thep-haloanisoles in acetic anhydride at -60°C. In the cases of p-fluoro-andp-chloro-anisole, addition of the nitronium ion is reversible and only small amounts of ipso products are obtained. With p-bromoanisole nitrodebromination occurs. When p-halophenyl ethers containing a trapping substituent, e.g., 2-(4-chlorophenoxy)-2-methylpropanoic acid, are used as substrates, substantial amounts of the spiro diene with nitro ipso to halogen, e. g., 3,3-dimethyl-8-chloro-8-nitro-l,4-dioxaspiro[4.5]deca-6,9-dien-2-one, can be isolated. ' The results demonstrate that extensive ipso attack at the halogen-substituted position is general in the nitration ofp-halophenyl ethers.

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