FourN⁷-alkoxybenzyl-substituted 4,5,6,7-tetrahydro-1H-pyrazolo[3,4-b]pyridine-5-spiro-1′-cyclohexane-2′,6′-diones: hydrogen-bonded supramolecular structures in zero, one, two or three dimensions

Abstract

3-tert-Butyl-7-(4-methoxybenzyl)-4',4'-dimethyl-1-phenyl-4,5,6,7-tetrahydro-1H-pyrazolo[3,4-b]pyridine-5-spiro-1'-cyclohexane-2',6'-dione, C(31)H(37)N(3)O(3), (I), 3-tert-butyl-7-(2,3-dimethoxybenzyl)-4',4'-dimethyl-1-phenyl-4,5,6,7-tetrahydro-1H-pyrazolo[3,4-b]pyridine-5-spiro-1'-cyclohexane-2',6'-dione, C(32)H(39)N(3)O(4), (II), 3-tert-butyl-4',4'-dimethyl-7-(3,4-methylenedioxybenzyl)-1-phenyl-4,5,6,7-tetrahydro-1H-pyrazolo[3,4-b]pyridine-5-spiro-1'-cyclohexane-2',6'-dione, C(31)H(35)N(3)O(4), (III), and 3-tert-butyl-4',4'-dimethyl-1-phenyl-7-(3,4,5-trimethoxybenzyl)-4,5,6,7-tetrahydro-1H-pyrazolo[3,4-b]pyridine-5-spiro-1'-cyclohexane-2',6'-dione ethanol 0.67-solvate, C(33)H(41)N(3)O(5) x 0.67C(2)H(6)O, (IV), all contain reduced pyridine rings having half-chair conformations. The molecules of (I) and (II) are linked into centrosymmetric dimers and simple chains, respectively, by C-H...O hydrogen bonds, augmented only in (I) by a C-H...pi hydrogen bond. The molecules of (III) are linked by a combination of C-H...O and C-H...pi hydrogen bonds into a chain of edge-fused centrosymmetric rings, further linked by weak hydrogen bonds into supramolecular arrays in two or three dimensions. The heterocyclic molecules in (IV) are linked by two independent C-H...O hydrogen bonds into sheets, from which the partial-occupancy ethanol molecules are pendent. The significance of this study lies in its finding of a very wide range of supramolecular aggregation modes dependent on rather modest changes in the peripheral substituents remote from the main hydrogen-bond acceptor sites.

Hydrogen-bonded chains of rings in 3-tert-butyl-1-phenyl-7-(4-trifluoromethylbenzyl)-4,5,6,7-tetrahydro-1H-pyrazolo[3,4-b]pyridine-5-spiro-1′-cyclohexane-2′,6′-dione and 3-tert-butyl-7-(4-methoxybenzyl)-1-phenyl-4,5,6,7-tetrahydro-1H-pyrazolo[3,4-b]pyridine-5-spiro-1′-cyclohexane-2′,6′-dione

“…1 and 2). Compounds (I) and (II) are related to the analogues (III) (Cruz et al, 2008) and (IV) (Trilleras et al, 2008) reported earlier, but they differ from these earlier examples in carrying no methyl substituents on the spirocyclohexane ring. Compounds (I) and (II) were synthesized using a straightforward modification of the synthetic method employed earlier (Cruz et al, 2008;Trilleras et al, 2008), using cyclohexane-1,3-dione in place of the 5,5-dimethylcyclohexane-1,3-dione used previously.…”

“…In continuation of our structural study of N 7 -benzyl-substituted pyrazolo[3,4-b]pyridine-5-spiro-1 0 -cyclohexane-2 0 ,6 0 -diones (Cruz et al, 2008;Trilleras et al, 2008), itself part of a programme exploring the use of multicomponent condensation reactions, especially those induced by microwave irradiation under solvent-free conditions, for the synthesis of novel heterocycles, we now report the molecular and supramolecular structures of the two title N 7 -benzyl derivatives (Figs. 1 and 2).…”

“…Displacement ellipsoids are drawn at the 30% probability level. dimethyl compounds (III) (Cruz et al, 2008) and (IV) (Trilleras et al, 2008). Firstly, both (III) and (IV) crystallize in the triclinic system, where (III) forms an ethanol hemisolvate, while compounds (I) and (II) both form monoclinic crystals.…”