4-ETHYL-4-ALLYL-2-CYCLOHEXEN-1-ONE

METHOXYCARBONYL-1,1,6-TRIMETHYL-1,4,4a,5,6,7,8,8a-OCTAHYDRO-2,3-BENZOPYRONE, an intramolecular Diels-Alder reaction is responsible for the diastereoselectivity. The stereoselective 1,4-functionalization of 1,3-dienes is exemplified by a two-step process leading to cis- and trans-1-ACETOXY-4-(DICARBOMETHOXYMETHYL)-2-CYCLOHEXENE. The effectiveness of a silyl hydride in providing a means for erythro-directed reduction of a p-keto amide is applied in a route to ERYTHRO-1 -(3-HYDROXY-2-METHYL-3-PHENYL-PROPANOYLJPIPERIDINE. This is followed by an asymmetric synthesis based on a chiral bicyclic lactam leading to (R)-4-ETHYL-4-ALLYL-2-CYCLOHEXEN-1-ONE. The stereoselectivity with which acetoxy migration can operate to an adjacent radical center is reflected in the one-step reaction that gives rise to 1,3,4,6-TETRA-O-ACETYL-2-DEOXY-a-D-GLUCOPYRANOSE. 

Albert 1. Meyers and Daniel Berney 55 ASYMMETRIC SYNTHESIS OF 4,4-DIALKYLCYCLOHEXENONES FROM CHIRAL BICYCLIC LACTAMS (R)-4-ETHYL-4-ALLYL-2-CYCLOHEXEN-1-ONE... 

Alternative preparations of 2-allyl-3-methylcyclohexanone include a) lithium-ammonia reduction of 2-allyl-3 methylcyclohex-2-enone (see Note 13), which can be prepared by alkylation of 3-methjdcyclohex-2-enone or by alkjdation of 4-carboethoxy-3-methylcyclohex-2-enone [Hagemann s ester 2-Cyclohexene-l-carboxylic acid, 2-inethyl-4-oxo-, ethyl ester], followed bj hydrolysis and decarboxylation and b) conjugate addition of lithium dimethylcupratc [Cuprate (1-), dimethyl-, lithium] to 2-cyolohexen-l-one followed by trapping of the enolate with allyl iodide or allyl bromidein an appropriate solvent. 

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