CHEMISTRY OF SPIRO-COMPOUNDS. PART I PREPARATION OF CYCLOPENTANE-SPIRQ-CYCLOPENTANONE AND CYCLOHEXANE-SPIRO-CYCLOHEPTANONE.

By the reduction of cyclopentanone and cyclohexanone with magnesium and aluminium amalgam dicyclopentane-diol and dicyclohexane diol respectively have been prepared. These dials are accompanied by a certain proportion of cyclopentylidene­cyclopentanone and cyclohexylidene-cyclohexanone. Dicyclopentatie-diol on being treated with sulphuric acid undergoes pinacone pinacoline transformation and gives cyclo­pentane-spiro-cyclohexanone. This on being oxidised yields cyclopentane-I-carboxy-I- butyric acid, which yields cyclopentane-spiro-cyclopentanone. Dicyclohexane-dial gives a mixture of cyclohexane-spiro-cycloheptanone and dicyclohexene