Giuseppe Bianchetti

Studies in the enamine field—XXIX : Autocondensation of 2-(N-methylanilino)-propene: 2,2,8,8-tetramethyl-spiro-[5.5]-undecane-4,10-dione☆

Abstract The reaction between acetone diethyl ketal and N-methylaniline yields as the main product a cyclic diketone which has been assigned the structure of 2,2,8,8-tetramethyl-spiro-[5,5]-undecane-4,10-dione on chemical and spectroscopic evidence.

Studies in the enamine field—XXX : Autocondensation products of 2-(methylanilino)-propene: 1-(2,2,6,6-tetramethyl-4-oxo-cyclohexyl)-5,5-dimethylcyclohexene-3-one☆

Abstract In the reaction between acetone diethyl ketal and N-methylanilie the main products 2,2,8,8-tetramethyl-spiro-[5.5]-undecane-4,10-dione (I) and six by-products were isolated and identified. Of these the most interesting is 1-(2,2,6,6-tetramethyl-4-oxo-cyclohexyl)-5,5-dimethylcyclohexene-3-one (IV) the structure of which was based on chemical and spectroscopic evidence. It was cyclized by alkali to 1-hydroxy-5,5,9,9,11,11-hexamethyltricyclo-[6,2,2,02, 7]-Δ2, 7-dodecene-3-one (VI). The structure of this compound was proved by spectroscopic methods and by reduction to the corresponding diol VIII.

v-Triazolines. Part III. cis-trans Equilibrium of 1-aryl-4,5-dihydro-v-triazoles

The stereochemical features of the reaction between 4-nitrophenyl azide and some enamines deriving from straight-chain aliphatic ketones or aryl alkyl ketones have been studied. Under kinetically controlled conditions the cis–trans equilibrium mixture of the enamine reacts with the azide, yielding exclusively the trans-triazoline. At higher temperature or in the presence of acidic catalysts, the trans-triazoline epimerizes, thus affording a cis–trans equilibrium mixture. The factors which affect the equilibrium position and the epimerization rate are discussed and a probable epimerization mechanism is suggested.