4-Methyl-1,3-bis(3,4-methylenedioxybenzyl)-2-(3,4-methylenedioxyphenyl)imidazolidine

In the title compound, C27H26N2O6, the imidazolidine ring adopts an envelope conformation. The methyl group on the imidazolidine ring is disordered over two positions with occupancies of 0.517 (11) and 0.483 (11), and the 3,4-methylenedioxyphenyl at the 3-position of imidazolidine ring is also disordered over two positions with occupancies of 0.60 (2) and 0.40 (2).

In the title compound, C 27 H 26 N 2 O 6 , the imidazolidine ring adopts an envelope conformation. The methyl group on the imidazolidine ring is disordered over two positions with occupancies of 0.517 (11) and 0.483 (11), and the 3,4-methylenedioxyphenyl at the 3-position of imidazolidine ring is also disordered over two positions with occupancies of 0.60 (2) and 0.40 (2).
In the title compound (I) (Fig.1), the imidazolidine ring adopts an envelope conformation. The methyl on the imidazolidine ring is disordered over two positions, leading to positional disorder of the two methylene H atoms of the ring, with occupancies of 0.517 (11) and 0.483 (11).
In the imidazolidine ring, the C-N bond lengths range from 1.435 (4) to 1.542 (4) Å, which are close the average single C-N bond lengths of 1.48 Å.

S2. Experimental
The reaction mixture containing 3,4-methylenedioxybenzaldehyde (3.0 g, 20 mmol) and propane-1,2-diamine (2.8 g, 20 mmol) was refluxed for about 4 h in ethanol (30 ml), then the borohydride sodium (1.52 g, 40 mmol) was added and stirred for 4 h (at 333-343 K), and the reaction mixture was cooled and the crude products were filtered off, washed with water and ethanol, then dried. Colourless crystals of (I) suitable for X-ray structure analysis were obtained by recrystallizing the crude product from ethanol (m.p. 478-480 K).

S3. Refinement
Methyl group on imidazolidine ring is disorder, and the 3,4-methylenedioxyphenyl at the 3-position on imidazolidine ring is also disorder. The site occupancies of the methyl group were refined to 0.517 (11) and 0.483 (11), and the site occupancies of the 3,4-methylenedioxyphenyl were refined to 0.60 (2) and 0.40 (2).
H atoms were placed in calculated positions with C-H = 0.93 (aromatic), 0.97 (methylene) and 0.96 Å (methyl), and refined in riding mode with U iso (H) = 1.5U eq (C) for methyl H atoms and 1.2U eq (C) for the others.

Figure 1
The molecular structure of (I), showing the disorder components and the atom-labelling scheme. Displacement ellipsoids are drawn at the 30% probability level.  Special details Geometry. All e.s.d.'s (except the e.s.d. in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell e.s.d.'s are taken into account individually in the estimation of e.s.d.'s in distances, angles and torsion angles; correlations between e.s.d.'s in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell e.s.d.'s is used for estimating e.s.d.'s involving l.s. planes. Refinement. Refinement of F 2 against ALL reflections. The weighted R-factor wR and goodness of fit S are based on F 2 , conventional R-factors R are based on F, with F set to zero for negative F 2 . The threshold expression of F 2 > σ(F 2 ) is used only for calculating R-factors(gt) etc. and is not relevant to the choice of reflections for refinement. R-factors based on F 2 are statistically about twice as large as those based on F, and R-factors based on ALL data will be even larger.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å 2 )
x y z U iso */U eq Occ.