SYNTHESIS AND STEREOCHEMISTRY OF 5-SUBSTITUTED 2-METHYLCYCLOHEPTANONES

The cis and trans isomers of 5-methyl- (2b), 5-isopropyl- (2c), 5-t-butyl- (2d), 5-isopropylol- (2e), and 5-carbethoxy-2-methylcycloheptanone (2f) were prepared in 80-90% yield via treatment of the appropriate 4-substituted cyclohexanone with diazoethane in 20% ethanol-ether. The initial (kinetic) distribution of the isomeric pairs was approximately 1:1. Equilibration of 2b-e in methanolic sodium carbonate afforded isomer distributions of 2.5:1 (2b), 2:1 (2c), 3:1 (2d), and 3:1 (2e), respectively, favoring the trans isomer in each case. Stereorational syntheses of trans-2,5-dimethylcycloheptanone and trans-2-methyl-5-isopropylolcycloheptanone were carried out to determine the stereochemistry of the products derived from the ring-expansion reactions. © 1968, American Chemical Society. All rights reserved.