Isoprene → 3-Cyclohexene-1-acetic acid, 4-methyl-

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When m is 1, n is 2 and p is 2, the ring system is a 2-oxabicyclo[3.2.2]nonane, another subclass of this invention. For example, compound XVp ##STR30## in which R2, R5 and R6 are methyl can be prepared by treating a Diels-Alder adduct of acrolein and isoprene with Ph3P=C(CH3)OCH3, hydrolyzing the resulting enol ether, treating the resulting ketone derivative with methyl magnesium bromide, and subjecting the resulting alcohol to epoxidation-cyclization to yield a 2-oxabicyclo[3.2.2.]nonan-7-ol, which is treated with WCH2X in which X is a halogen atom to yield the desired ether, XVp. Alternatively, 4-methyl-3-cyclohexene-1-acetic acid, as obtained by the method of Kugatova-Shemyakina et al., Chemical Abstracts, 65:10504c (1966) is treated with methyl Grignard followed by epoxidation-cyclization of the resulting alcohol to yield a 2-oxabicyclo[3.2.2]nonan-7-ol.

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