Quasi-nature catalysis: Developing catalysts in air and water, and their applications in natural product synthesis
Description
The research consists of mainly two components: Development of novel methodologies using organometallic species in water and air; utilizing these methodologies as a key step in the total synthesis of natural products The first chapter gives a brief introduction on the use of water as a solvent for organic reactions. It gives an idea about the advantages of using water as a solvent. Several examples of organometallic reactions that are reported in the literature are highlighted to justify the need to develop aqueous organometallic chemistry In the second chapter, Ullmann-type coupling of aryl halides which are usually done using stoichiometric amount of copper and at high temperatures are carried out in water and air using palladium as catalyst in the presence of a catalytic amount of 18-crown-6 at room temperature. The presence of the crown ether serves to increase the isolated yield by possibly stabilizing the intermediate The third chapter concentrates on rhodium(I) complexes catalyzed reactions in water. Rhodium(I) complexes were used to catalyze the conjugate addition of triphenylbismuth with unsaturated carbonyl compounds. In order to expend the scope of the reaction to other substrates, the tin analogues were also successfully studied. The final section of this chapter covers the tandem hydrosilation-aldol condensation reaction between unsaturated carbonyl compounds and aldehydes catalyzed by Rh(I) complexes In the fourth chapter, ruthenium complexes are shown to insert into the C-H bond and subsequently add to electron rich alkenes in water. In the final chapter, indium(I) chloride is shown to have additional advantages over indium metal in mediating carbonyl addition reactions in water. The stereoselectivity offered by indium(I) chloride was used as a key step in the total synthesis of (+)-Altholactone and epi---Gonioheptolide-A