Root growth promoters, 4-hydroxykigelin (1) and 6-demethylkigelin (2), together with 6-hydroxymellein (3) were isolated from cultures of the fungus Aspergillus terreus and their structures were identified by spectroscopic analysis. The biological activities of the three dihydroisocoumarins, 1, 2, and 3, have been examined using a bioassay method with lettuce seedlings. Furthermore, interactions...

The molecule of the title compound, C(18)H(14)N(4), lies on a center of inversion such that there is one half-mol-ecule in the asymmetric unit. The N-N single bond adopts a trans configuration and the indole fused-ring system is nearly coplanar with the -CH=N-N=CH- fragment [dihedral angle = 9.8 (2)°]. Adjacent mol-ecules are linked by indole-azine N-H⋯N hydrogen bonds into a layer motif.

Planar (r.m.s. deviation from the plane through all non-H atoms = 0.036 Å) mol-ecules of the title compound, C(16)H(11)BrO(2), form a layered structure stabilized by C-H⋯O hydrogen bonds and π-π stacking inter-actions.

In the title compound, C(12)H(12)N(2)O, the azetidine ring (r.m.s. deviation = 0.021 Å) and the oxetane ring (r.m.s. deviation = 0.014 Å) are nearly perpendicular to each other [dihedral angle = 89.7 (1)°]. The azetidine ring is twisted out of the plane of the benzene ring by 18.3 (1)°. In the crystal structure, mol-ecules are linked to form chains along the c axis by C-H⋯O hydrogen bonds.

It is shown that a 4-(12,6,6) design, if it exists, must be rigid. The intimate relationship of such a design with 4-(12,5,4) designs and 5-(12,6,3) designs is presented and exploited. In this endeavor we found: (i) 30 nonisomorphic 4-(12,5,4) designs; (ii) all cyclic 3-(11,5,6) designs; (iii) all 5-(12,6,3) designs preserved by an element of order three fixing no points and no blocks; and (iv)...