Many naturally occuring compounds are useful as chiral ligands, as illustrated by sparteine. Indeed, (-)-Sparteine, a natural chiral diamine, has been used successfully in asymmetric synthesis. However, it has important limitations. Inspired by these bio-derived ligands, our group has worked on the development of a family of novel diaminoligands that could act as chirality source in chemical transformations performed in water-based solvents as a greener approach to large scale transformations. We have explored a strategy to prepare chiral N,N'-dimethylpiperazines that possess features of sparteine. Such diamines could potentially be used as a source of chirality in various enantioselective chemical reactions. To obtain chiral N,N'-dimethylpiperazines, an efficient strategy using solid-phase peptide synthesis on oxime resin was developed with natural and non-natural amino acids. Cyclization-cleaveage of dipeptides from the resin leads to the formation of diketopiperazines, which were then transformed into the desired diamines ligands. We will report our results on the development of the strategy and present applications of the newly prepared diamines ligands in enantioselective synthesis.

Synthesis and characterization of bio-inspired ligands for enantioselective "green" transformations

248th National Meeting (2014)

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