The Menthane Class

Escher, U. Keller, and B. Willhalm, Helv. Chim. Acta, 1979, 62, 2061. 

Takashashi, T. Someya, S. Muraki, and T. Yoshida, Agric. Biol. Chem., 1980, 44, 1535. 

Sasaki, H. Taguchi, T. Endo, I. Yosioka, and Y. Iitaka, Chem. Pharm. Bull., 1981,29,1636. 284 I. Sakata and K. Koshimizu, Agric. Biol. Chem., 1978, 42, 1959. 

A mixture of o-menthanes resulted from reduction of o-cymene with Ca(NH3)6,297 and a neat route to the o-menthane skeleton involved photochemical addition of allene to 3-methylcyclohex-2-en-l-one and opening of the cyclobutyl ring with BF3.298 O-Menthadi- and tri-enes resulted from pyrolysis of verbenene.299 Acid-and base-promoted isomerizations of o-menthadienes300 and dehydration of cis- and trans- o-menthan-8-ols with a variety of reagents have been recorded.301 Optically active 2-methyl-4-isopropenylcyclohexanone (which is a useful precursor for ra-menthane derivatives) has been prepared by pyrolysis of chiral 2,2,5-trimethyl-bicyclo[3.1.1 ]heptan-2-one.302 

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