Multicomponent reactions for the synthesis of fluorinated organic compounds and related chemistry

2011-11-01Development of eco- and aqueous friendly, stable and recyclable catalysts for organic synthesis is one of the major steps in safe, environmentally benign and sustainable practice of chemistry. This dissertation is devoted to the preparation of novel solid Lewis acid catalysts and their application in the synthesis of both fluorinated and non-fluorinated biologically important molecules. It focuses on the development of sustainable methodology for the synthesis of α-amino nitriles and variety of heterocyles such as 3,4- dihydropyrimidininones, benzimidazolines, dihydrobenzoxazinones, which serve as important building blocks for drug discovery. It also describes the new methodology for the synthesis of α-alkyl-α-fluoromethylenebisphosphonates. ❧ Chapter 1 gives a general review of solid acid catalysts and discusses their need in the development of ""green"" catalysis. ❧ Chapter 2 describes the synthesis of various α-amino nitriles, precursors of vital α-amino acids via Strecker reaction employing ""green"" catalysts such as Nafion-H and its silica nanocomposite Nafion SAC-13. Preparation of Nafion-Fe, a Lewis acid version of Nafion-H and its application in ketonic Strecker reaction are also described. ❧ In Chapter 3, an efficient one-pot synthesis of biologically important 3,4- dihydro-pyrimidininones by three-component Biginelli reaction employing Ga(OTf)₃ as catalyst is disclosed. The preparation of novel thiazine-type products and mechanism of their formation is discussed. ❧ In Chapter 4, the preparation and application of novel Lewis acid catalyst Nafion-Ga, gallium salt of Nafion-H in synthesis of 3,4- dihydropyrimidininones by Biginelli reaction and benzimidazolines, dihydrobenzoxazinones by condensation-cyclization reactions is expounded. ❧ Chapter 5 deals with the development of a new method for the synthesis of α-alkyl-α-fluoromethylenebisphosphonates, potential antiresorptive drugs