Date of Award
Campus Access Dissertation
Doctor of Philosophy (PhD)
Nitrogen containing heterocyclic compounds such as indoles, carbazoles, quinolines, β-carbolines, indolines and pyrazolopyrimidines are present in extensive number of biologically active compounds of natural or synthetic origin. These heterocyclic moieties are of exceptional interest not only in the pharmaceutical and agrochemical industries but also in non-biological applications such as organocatalysis and photochemistry. Due to their widespread applications in various fields the synthesis and functionalization of heterocyclic compounds has always been at the cutting edge of organic chemistry research. The increasing number of applications of heterocyclic compounds provides an incentive for developing new methods for their syntheses. Due to ever-strengthening environmental regulations and safety concerns the design and development of environmentally sustainable synthetic methods is highly desirable. While very effective, the traditional syntheses of these compounds involve the use of a variety of reagents/catalysts which are not environmentally compatible, produce a large amount of waste and require multiple steps and long reaction times. Therefore, the design of improved and environmentally benign approaches for their preparation is of prime importance. Various environmentally benign methods for the synthesis and functionalization of these compounds were developed by microwave assisted approach and/or heterogeneous catalysis.
Carbazoles, quinolines, and β-carbolines were synthesized by K-10 montmorillonite catalyzed cyclization/aromatization method. In all the cases, reactions were completed in short reaction times with excellent yields and selectivities. This method has successfully demonstrated the use of K-10 as an effective, environmentally benign and recyclable solid acid catalyst for various cyclization/aromatization reactions using commercially available starting materials.
Heterogeneous catalytic hydrogenation reactions of various indoles and quinolines catalyzed by commercially available and inexpensive Pd/C or Pt/C catalysts were carried out. When hydrogenated in Pd/C-HCOOH system, various indoles and quinolines formed the corresponding N-formylindolines and N-formyltetrahydroquinolines. Hydrogenation of indoles using Pt/C catalyst in water gave the corresponding indolines in excellent yields and 100% selectivities. Hydrogenation of indoles to indolines in a heterogeneous system using H2 as a hydrogen source has for long been a difficult problem.
In addition, pyrazolopyrimidines were synthesized to study the inhibition of Phospholipase-D enzyme. Indole-based organofluorine inhibitors were synthesized and investigated as potential inhibitors for amyloid fibrillogenesis.
Kulkarni, Aditya M., "Heterogeneous Catalytic Processes for the Synthesis and Functionalization of N-Heterocycles and Fine Chemicals" (2011). Graduate Doctoral Dissertations. 39.