IRO[1'(2',4',5'-TRIMETHYLCYCLOHEXANE)]-6-ENE-4-ONE

In order to synthesize cyclic alpha-amino acids the dienophile lidene- 2,10,10-trimethyl-3-oxa-6-azatricyclo-[7.1. 1.0(2,7)]undeca-6-ene-4-on e, (1), which has a pinane nucleus which acts as a chiral inductor, wa s prepared. The Diels-Alder reaction of (1) with 2,3-dimethyl-1,3-buta diene gives one diastereoisomer, the hydrogenation of which leads to a n equimolecular mixture of the title compound, e-5-spiro-1'-(2',4',5'- trimethylcyclohexane)-4-one (4), C20H30NO2, and its enantiomer. The cr ystal structure determination of the title compound establishes the re lative stereochemistry of the Diels-Alder product.