R. Ramu

Remarkable DNA binding affinity and potential anticancer activity of pyrrolo[2,1-c][1,4]benzodiazepine–naphthalimide conjugates linked through piperazine side-armed alkane spacers

A series of pyrrolobenzodiazepine-naphthalimide conjugates tethered through a piperazine ring system have been designed, synthesized, and evaluated for their anticancer activity. These new conjugates exhibit very high DNA binding affinity and cytotoxic activity against a number of cell lines.

Efficient, selective deprotection of aromatic acetates catalyzed by Amberlyst-15 or iodine

Aromatic acetates were selectively deprotected in the presence of aliphatic acetates to the corresponding phenols in excellent yields using Amberlyst-15 or iodine as catalysts in methanol at room temperature. The first catalyst can be recovered.

Spectroscopic and calorimetric studies on the DNA recognition of pyrrolo[2,1-c][1,4]benzodiazepine hybrids

DNA binding of two hybrid ligands composed of an alkylating pyrrolo[2,1-c][1,4]benzodiazepine (PBD) moiety tethered to either a naphthalimide or a phenyl benzimidazole chromophore was studied by DNA melting experiments, UV and fluorescence titrations, CD spectroscopy and isothermal titration calorimetry (ITC). Binding of both hybrids results in a remarkable thermal stabilization with an increase of DNA melting temperatures by up to 40 degrees C for duplexes that allow for a covalent attachment of the PBD moiety to guanine bases in their minor groove. CD spectroscopic measurements suggest that the naphthalimide moiety of the drug interacts through intercalation. In contrast, the PBD-benzimidazole hybrid binds in the DNA minor groove with a preference for (A,T)(4)G sequences. Whereas the binding of both ligands is enthalpy-driven and associated with a negative entropy, the benzimidazole hybrid exhibits a less favourable binding enthalpy that is counterbalanced by a more favourable entropic term when compared to the naphthalimide hybrid.

Synthesis of pyrano and furanoquinolines using silica chloride or amberlyst-15 as a heterogeneous catalyst

The coupling of three components, anilines, benzaldehydes and 3,4-dihydro-2H- pyran or 2,3-dihydrofuran to prepare the corresponding pyrano or furanoquinolines has been achieved efficiently using silica chloride or Amberlyst-15 as a heterogeneous catalyst. Amberlyst-15 can be recovered and reused.

Silica‐Supported Sodium Hydrogen Sulfate Catalyzed Facile Transformation of p‐Hydroxybenzyl Alcohols to p‐Hydroxybenzyl Ethers and Thioethers

Abstract The heterogeneous catalyst, silica‐supported sodium hydrogen sulfate (NaHSO4 · SiO2) has been found to be highly efficient in carrying out the transformation of p‐hydroxybenzyl alcohols at room temperature to p‐hydroxybenzyl ethers and thioethers in very high yields. #Part 31 in the series, “Studies on Novel Synthetic Methodologies,” For part 30 see Ref.1

Perchloric acid adsorbed on silica gel : an efficient heterogeneous reusable catalyst for synthesis of 1,5-benzodiazepines

The condensation of o-phenylenediamines with both aliphatic (acyclic and cylic) and aromatic ketones has been carried out to produce 1,5-benzodiazepines in high yields using perchloric acid adsorbed on silica gel as a heterogeneous catalyst. The catalyst can be recycled.