title: Folded conformations due to arene interactions in dissymmetric and symmetric butylidene-linker models based on pyrazolo[3,4-d]pyrimidine, purine and 7-deazapurine.
abstract: The butylidene-linker models 1-[2-(2,6-dimethylsulfanyl-9H-purin-9-yl)-2-methylidenepropyl]-4,6-bis(methylsulfanyl)-1H-pyrazolo[3,4-d]pyrimidine, C18H20N8S4, (XI), 7,7'-(2-methylidenepropane-1,3-diyl)bis[3-methyl-2-methylsulfanyl-3H-pyrrolo[2,3-d]pyrimidin-4(7H)-one], C20H22N6O2S2, (XIV), and 7-[2-(4,6-dimethylsulfanyl-1H-pyrazolo[3,4-d]pyrimidin-1-yl)-2-methylidenepropyl]-3-methyl-2-methylsulfanyl-3H-pyrrolo[2,3-d]pyrimidin-4(7H)-one, C19H21N7OS3, (XV), show folded conformations in solution, as shown by (1)H NMR analysis. This folding carries over to the crystalline state. Intramolecular π-π interactions are observed in all three compounds, but only (XIV) shows additional intramolecular C-H···π interactions in the solid state. As far as can be established, this is the first report incorporating the pyrrolo[2,3-d]pyrimidine nucleus for such a study. In addition to the π-π interactions, the crystal structures are also stabilized by other weak intermolecular C-H···S/N/O and/or S···N/S interactions.
authors.affiliation: Medicinal and Process Chemistry Division, Central Drug Research Institute, Lucknow 226 031, India.
authors.forename: Kamlakar
authors.initials: K
authors.lastname: Avasthi
authors.affiliation: Medicinal and Process Chemistry Division, Central Drug Research Institute, Lucknow 226 031, India.
authors.forename: Lakshmi
authors.initials: L
authors.lastname: Shukla
authors.affiliation: Molecular and Structural Biology Division, Central Drug Research Institute, Lucknow 226 031, India.
authors.forename: Ruchir
authors.initials: R
authors.lastname: Kant
authors.affiliation: Department of X-ray Crystallography, IICT Hydeabad, Hyderabad 500 007, India.
authors.forename: Krishnan
authors.initials: K
authors.lastname: Ravikumar
mesh_terms: D018360:Crystallography, X-Ray; D006860:Hydrogen Bonding; D009682:Magnetic Resonance Spectroscopy; D008968:Molecular Conformation; D011687:Purines / Q000737:chemistry*; D011720:Pyrazoles / Q000737:chemistry*; D011743:Pyrimidines / Q000737:chemistry*; D011758:Pyrroles / Q000737:chemistry*
chemical_list: C000590239:1-(2-(2,6-dimethylsulfanyl-9H-purin-9-yl)-2-methylidenepropyl)-4,6-bis(methylsulfanyl)-1H-pyrazolo(3,4-d)pyrimidine; C000590241:7,7'-(2-methylidenepropane-1,3-diyl)bis(3-methyl-2-methylsulfanyl-3H-pyrrolo(2,3-d)pyrimidin-4(7H)-one); C512929:7-deazapurine; D011687:Purines; D011720:Pyrazoles; D011743:Pyrimidines; D011758:Pyrroles; C014175:pyrazolo(3,4-d)pyrimidine; C030986:pyrimidine; C030985:purine
keywords: 7-deazapurine; arene interactions; butylidene linker; crystal structure; folded conformations; purine; pyrazolo[3,4-d]pyrimidine