Stereochemistry of the addition of a grignard reagent to terpene ketones with seven-membered rings

The dehydration of 1,2,5,5- and 1,2,6,6,-tetramethylcycloheptanols by the POCl₃/Py system has been studied. It has been established that the products of the dehydration of 1,2,5,5-tetramethylcycloheptanols are 1,2,5,5- and 1,4,4,7-tetramethylcycloheptenes, and those of the dehydration of 1,2,6,6-tetramethylcycloheptanols are 1,3,3,7- and 1,2,4,4-tetramethylcycloheptenes. On the basis of the results of dehydration by the POCl₃/Py system it has been shown that the Grignard reactions of 2,5,5- and 2,6,6-trimethylcycloheptanols form mainly tertiary alcohols with the trans orientation of the vicinal OH and CH₃ groups.