| Popis: |
Asymmetric cyanohydrin synthesis is a broad and developing area of organic chemistry to which many groups have contributed over the years. Notably, North et al have developed highly active salen based catalysts 1 and 2 for the asymmetric addition of cyanide to aldehydes. More recent mechanistic investigations have revealed that combining complexes 1 and 2 gave interesting results indicating the possible formation of and catalysis by a new heterobimetallic complex formed in-situ. This thesis follows on from the initial study and offers good evidence for the formation of a mixed metal bimetallic catalyst possessing characteristics of each parent complex. Firstly, the catalysed addition of trimethylsilyl cyanide, potassium cyanide and ethyl cyanoformate to benzaldehyde was studied (Scheme 1) using various chiral and achiral analogues of complexes 1 and 2 to study the effects on cyanohydrin product enantiometric excess and absolute configuration. |
