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Title: Asymmetric Transfer Hydrogenation & Transfer Hydrogenation in Water
Author: Feng Wu, Xiao
ISNI:       0000 0001 3459 4482
Awarding Body: University of Liverpool
Current Institution: University of Liverpool
Date of Award: 2007
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Asymmetric transfer hydrogenation (ATH) has emerged as a practical, powerful alternative to asymmetric hydrogenation for the production of chiral alcohols, one of the most valuable intermediates in the synthesis of pharmaceuticals, flavour, aroma and agricultural chemicals, and speciality materials. However, the application of ATH has been hampered by its low TONs and TOFs in the past. On the other hand, enabling catalysis in water contributes to one of the most important and challenging fields of modem chemistry, green synthesis. As a solvent for organic reactions, water bears a number of attractive physical-chemical properties over traditional organic molecular solvents. A~ will be seen in the thesis, ATH in neat water has proved to be viable, affording chiral alcohols in fast rates, high productivity and high enantioselectivity. The reduction can be carried out with unmodified or tailor-made catalysts by using mild, readily available formate salt as reductant with no organic solvents required. A series of ligands (L =chiral diamine and its derivatives, amino alcohols) and metal complexes (those of Ru, Rh and Ir) have been explored for the ATH in water, and a wide range of ketones have been efficiently reduced to chiral alcohols (Scheme A-I.) Furthermore, for the PEG-supported catalyst, water as solvent, it can be very easy to separate the catalyst from the product by simple phase separation, which is a very important and ideal dream, especially in pharmaceutical applications. Aldehydes are hard to reduce successfully by TH catalysis in the solvent which is normally used for TH of ketones, such as refluxing 2-propanol, azeotropic formic acid and triethylamine mixture. However, this water-formate reducing system can also apply to the TH of aldehydes, furnishing highly chemoselectivity and remarkably fast reaction rate for the reduction of aldehydes. Thus, the in-water reduction provides a new method that is simple, economical and eco-friendly, and can be readily adapted for laboratory synthesis and commercial-scale production.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available