Development of organo- and metal-catalyzed reactions with water as the solvent.
Leong, Wendy Wen Yi.
Date of Issue2013
School of Physical and Mathematical Sciences
The work described in this thesis is devoted to the development of environmentally benign organo- and metal-catalyzed reactions through the use of water as the solvent. With the use of a “designer surfactant”, TPGS-750-M, copper-catalyzed conjugate additions in water using organozinc reagents formed in situ were successfully achieved. This methodology could be applied to a broad spectrum of substrates, affording the desired 1,4-adducts in good to excellent yields. NHC-catalyzed reactions involving enals were shown to take place efficiently with water as the only solvent. The simple and mild reaction conditions, often without the need for an inert atmosphere, low catalyst loading and the desirable characteristics of water, make this an attractive methodology for large scale synthesis. Deuterated compounds could also be synthesized easily and inexpensively by using D2O as the solvent. The synthesis and evaluation of TADDOL-based phosphoric acids in organic solvent were carried out. In addition, the PQS-BINAP-Rh catalyst was synthesized and applied to the asymmetric hydrogenation and 1,4-addition of arylboronic acids to fumaric compounds in water. These studies lay the foundation for PQS-bound phosphoric acid catalyzed reactions in water which allow for recycling of the catalyst.