Rational design and synthesis of receptors for carboxylates

This thesis is concerned with the synthesis and subsequent investigation of the properties of thiourea based receptors for amino acid carboxylate derivatives. Chapter two describes the synthesis of novel bisthiourea pyrrolidines such as 123, which were found to form tightly bound dimers and were consequently unsuitable for the complexation of carboxylate salts. Chapter three describes the synthesis of pyridyl thiourea tweezer receptors, which were found to form well defined complexes with a range of carboxylates. Attention is also given to the level of conformational control (preorganisation) present in the receptor. Both the thiourea and amide hydrogens present in 161 were involved in forming hydrogen bonds to the carboxylate syn and anti lone pairs and receptor 161 bound a range of chiral carboxylates with enantioselectives of up to 2:1. Having probed the properties of tweezer based receptors, chapter four goes on to describe the synthesis of a novel bisthiourea based macrocycle 193 and examines its behaviour with the N-Boc protected dicarboxylate salts of glutamate and aspartate. (Fig. 8567).