POLYMORPH(II) OF METHYL MINOBENZYL)-1,2,2-TRIMETHYLCYCLOPENTANECARBOXYLATE

The title compound, C19H27NO4, is an intermediate product in the synth esis of oxazepinic and piperidinic compounds. Two crystalline forms of the title compound have been obtained but only one [form (II)] gave s uitable crystals for X-ray structure analysis. The five-membered ring has an envelope conformation with C(2) 0.60 (5) angstrom out of the pl ane defined by the other four atoms. It has been established that the oxime group has a syn conformation and the two enantiomers form a dime r around the centre of symmetry by means of hydrogen bonds between the ir oxime groups.