Naturally occurring polyquinanes have attracted considerable attention from the viewpoints of challenging targets for total syntheses and their biological activities.1 During the course of our continuous investigation on stereoselective syntheses of hetero angular polyquinane analogues from active urazoles (1a-b) 2 , we isolated an intricate cyclic bisurea including an indoline skeleton (title compound, 2) by an alkali-treatment of photoadduct (3) of 1b with ethanol. Since the 1 H and 13 C-NMR analyses did not permit an identification of the framework and the stereochemistry of 2, the crystal structure was determined by an X-ray analysis.The synthetic procedure of 2 was as follows. A powder of sodium hydroxide (150 mg) was added to an ethanolic solution (20 ml) of 3 (100 mg) and heated at reflux for 5 h. After removing the solvent on a rotary evaporator, the resulting solid was chromatographed on silica gel with dichloromethane as an eluent. The isolated pure-white solid (62% yield) was recrystallized from ethanol to afford crystals appropriate for an X-ray analysis.An X-ray analysis of the colorless crystal was performed on a Rigaku AFC7R diffractometer with graphite monochromated Cu K α radiation (λ=1.5418 Å). The detailed measurement conditions and crystal data are listed in Table 1. The intensity data were collected at 23˚C using the ω -2θ scan technique to a maximum 2θ value of 120.1. Of the 3473 reflections collected, 3218 were unique (R int =0.013).The structure was solved by a direct method with SIR92. 3 The non-hydrogen atoms were refined anisotropically. All hydrogen atoms were placed at calculated positions with their isotropic thermal parameters. The positional parameters are given in Table 2. The selected bond lengths and angles are listed in Tables 3 and 4, respectively. An ORTEP drawing of 2 is illustrated in Fig. 2.The structure of 2 consists of one indoline and two imidazolidinone rings, and these rings are fused at the axis of N2-C3 and of C1-C3. The dihedral angle between the least-squares planes of the indoline ring and the two imidazolidinone rings are 46.6˚ and 84.0˚, 817 ANALYTICAL SCIENCES AUGUST 1999, VOL. 15 1999