S. Maharani

rac-2-Hy­droxy-2-(2-oxocyclo­pent­yl)-1H-indene-1,3(2H)-dione

In the title compound, C(14)H(12)O(4), the indene unit is essentially planar [r.m.s. deviation = 0.0309 (1) Å] and the cyclo-penta-none ring adopts a twist form. In the crystal, mol-ecules are joined via pairs of O-H⋯O hydrogen bonds into centrosymmetric dimers.

Synthesis of penta- and tetra-cyclic cage-like compounds and dispiro heterocycles through microwave-assisted solvent-free multi-component domino reactions

Novel penta- and tetra-cyclic cage-like compounds and dispiro heterocycles were obtained as a result of the microwave-assisted three-component domino reactions of heterocyclic or carbocyclic ketones, ninhydrin and sarcosine under solvent- and catalyst-free conditions. Interestingly, heterocyclic ketones afforded fused polycyclic cage-like compounds, whereas the carbocyclic ketones led to the formation of dispiro heterocycles.

Crystal structure of 2-benzyl-amino-4-(4-bromo-phen-yl)-6,7-di-hydro-5H-cyclo-penta-[b]pyridine-3-carbo-nitrile.

The packing of the title compound features N—H⋯N hydrogen bonds, which form inversion dimers, and weak aromatic π–π stacking interactions.

Crystal structures of 2-benzyl­amino-4-(4-bromo­phen­yl)-6,7,8,9-tetra­hydro-5H-cyclo­hepta­[b]pyridine-3-carbo­nitrile and 2-benzyl­amino-4-(4-chloro­phen­yl)-6,7,8,9-tetra­hydro-5H-cyclo­hepta[b]pyridine-3-carbo­nitrile

In two cyclohepta[b]pyridine-3-carbonitrile derivatives, the cycloheptane ring adopts a half-chair conformation. In the crystals of both compounds, pairs of N—H⋯Nnitrile hydrogen bonds link the molecules, forming inversion dimers with (12) ring motifs.

Crystal structure of 2-benzyl­amino-4-p-tolyl-6,7-di­hydro-5H-cyclo­penta­[b]pyridine-3-carbo­nitrile

In the crystal of the title compound, molecules are linked by pairs of N—H⋯Nnitrile hydrogen bonds, forming inversion dimers with an (12) ring motif. The dimers are linked by C—H⋯π and π–π interactions [centroid–centroid distance = 3.7211 (12) Å], forming a three-dimensional framework.

C-H···O and C-H···N interactions in three hexahydrocycloocta[b]pyridine-3-carbonitriles.

The structures of three new pyridine derivatives, 2-methoxy-4-(4-methoxyphenyl)-5,6,7,8,9,10-hexahydrocycloocta[b]pyridine-3-carbonitrile, C20H22N2O2, (I), 2-ethoxy-4-(3-nitrophenyl)-5,6,7,8,9,10-hexahydrocycloocta[b]pyridine-3-carbonitrile, C20H21N3O3, (II), and 2-ethoxy-4-(4-methoxyphenyl)-5,6,7,8,9,10-hexahydrocycloocta[b]pyridine-3-carbonitrile, C21H24N2O2, (III), differ in the nature of the substituents either at the 2-position of the central pyridine ring or on the pendent aryl ring. This simple change in the structure substantially alters the intermolecular interaction patterns. The substituted phenyl group adopts a synclinal geometry with respect to the plane of the pyridine ring in all three compounds. In (I), a C-H···N interaction results in a one-dimensional chain parallel to the b axis. In (II), there are two C-H···N(nitrile) interactions from different symmetry-related molecules, resulting in a two-dimensional network parallel to the bc plane. There is also a weak C-H···O interaction from the ethoxy group to an adjacent nitro O atom. The present work is an example of how the simple replacement of a substituent in the main molecular scaffold may transform the structure type, paving the way for a variety of supramolecular motifs and consequently altering the complexity of the intermolecular interaction patterns.