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Links to deliverables and publications from FP7 projects, as well as links to some specific result types such as dataset and software, are dynamically retrieved from OpenAIRE .
Exploitable results
During the course of this grant, a new class of catalysts for the asymmetric addition of cyanide to aldehydes was developed. The catalysts were the titanium(IV) complexes of chiral salen ligands. A large number of different ligands were examined including C2 symmetric ligands derived from (R,R)-cylcohexanediamine, C1 symmetric ligands derived from amino acids, and ligands incorporating chiral paracyclophane units. The best ligand was the (R,R)-cylcohexanediamine derivative with di-t-butyl substituents on each aromatic ring. This ligand, when complexed to titanium tetrachloride induced the asymmetric addition of trimethylsilyl cyanide to aldehydes producing cyanohydrin silyl ethers with up to 90% enantiomeric excess. Remarkably, these reactions could be carried out at room temperature and using as little as 0.1mol% of the catalyst. This makes this catalyst the most active catalyst yet discovered for the asymmetric addition of trimethylsilyl cyanide to aldehydes.
Detailed mechanistic studies have been carried out on this catalyst system, and it was found that high enantiomeric excesses were only obtained when water was present in the reaction mixture. The water was found to react with the initial complex to form a dimeric structure which is more reactive than the monomer. The structure of the dimer was determined by X-ray crystallography, and it was found to react with trimethylsilyl cyanide to form a new catalyst, the structure of which is still being determined.
The other part of this INTAS project concerned the development of new ligands derived from paracyclophane as alternatives to ligands derived from ferrocene. Considerable success was achieved in the synthesis of paracyclophane derivatives substituted with formyl and hydroxyl groups, and methodology is being developed to allow the synthesis of phosphine substituted paracyclophanes. Already, the chiral paracyclophanes have been shown to produce highly active catalysts for the asymmetric addition of cyanide to aldehydes, and to function as chiral auxiliaries for asymmetric amino acid synthesis.
During the course of this grant, two of Prof. Belokon's co-workers spent time working in Bangor, and a third spent time in Rostock. One of Prof. Belokon's students spent three months in Paris, and one of Dr. Rozenberg's students spent three months in Oxford. A number of Dr. Saygan's co-workers also spent time working in Moscow with Prof. Belokon. Towards the end of the grant; all of the participants met for a two day conference in Oxford, and throughout the grant there had been smaller meetings involving two or three of the participants. The main achievement of the INTAS grant has been to strengthen the collaboration between the participants, a collaboration which is continuing thanks to funds obtained from elsewhere.
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