Crystal structures of the synthetic inter­mediate 3-(6-chloro-7H-purin-7-yl)meth­ylcyclo­butan-1-one and of two oxetanocin derivatives: 3-(6-chloro-89-di­hydro-7H-purin-7-yl)meth­ylcyclo­butan-1-ol and 3-(6-chloro-9H-purin-9-yl)meth­ylcyclo­butan-1-ol

摘要

The crystal structures of an inter­mediate, C10H9ClN4O, 3-[(6-chloro-7H-purin-7-yl)meth­yl]cyclo­butan-1-one (I), and two N-7 and N-9 regioisomeric oxetanocin nucleoside analogs, C10H13ClN4O, 3-[(6-chloro-8,9-di­hydro-7H-purin-7-yl)meth­yl]cyclo­butan-1-ol (II) and C10H11ClN4O, 3-[(6-chloro-9H-purin-9-yl)meth­yl]cyclo­butan-1-ol (IV), are reported. The crystal structures of the nucleoside analogs confirmed the reduction of the N-7- and N-9-substituted cyclo­butano­nes with LiAl(OtBu)3 to occur with facial selectivity, yielding cis-nucleosides analogs similar to those found in nature. Reduction of the purine ring of the N-7 cyclo­butanone to a di­hydro­purine was observed for compound (II) but not for the purine ring of the N-9 cyclo­butanone on formation of compound (IV). In the crystal of (I), mol­ecules are linked by a weak Cl⋯O inter­action, forming a 21 helix along [010]. The helices are linked by offset π–π inter­actions [inter­centroid distance = 3.498 (1) Å], forming layers parallel to (101). In the crystal of (II), mol­ecules are linked by pairs of O—H⋯N hydrogen bonds, forming inversion dimers with an R ² 2(8) ring motif. The dimers are linked by O—H⋯N hydrogen bonds, forming chains along [001], which in turn are linked by C—H⋯π and offset π–π inter­actions [inter­centroid distance = 3.509 (1) Å], forming slabs parallel to the ac plane. In the crystal of (IV), mol­ecules are linked by O—H⋯N hydrogen bonds, forming chains along [101]. The chains are linked by C—H⋯N and C—H⋯O hydrogen bonds and C—H⋯π and offset π–π inter­actions [inter­centroid distance = 3.364 (1) Å], forming a supra­molecular framework.