Spiranes. V. A synthetic route to symmetrical and unsymmetrical 3,9-diazaspiro [5.5]undecanes†

The synthesis of derivatives of the hitherto unreported 3,9-diazaspiro[5,5]undecane has been accomplished. Starting from the dianhydride of methanetetraacetic acid or from N-methyl-4-piperidone, synthetic paths have been developed which permit the preparation of either symmetrical or unsymmetrical derivatives.