Synthesis of chiral aza crown ethers having exocyclic hydroxy groups and their use in asymmetric reduction of ketones with sodium tetrahydridoborate

New chiral diaza crown ethers with exocyclic hydroxy groups were synthesized by reactions of (2S,3S)-1,4-dibenzyloxy-2,3-bis(2-oxiranylmethoxy)butane with N,N'-dibenzyl-1,2-ethanediamine and (4S,5S)-4,5-bis(benzylaminomethyl)-2,2-dimethyl-1,3-dioxolane. Catalytic debenzylation of the products gave the corresponding derivatives having secondary amino groups. The obtained diaza crown ethers, as well as some known crown ethers, were used as asymmetric catalysts in the reduction of pinacolone and acetophenone with sodium tetrahydridoborate in methylene chloride. Depending on the catalyst structure, the optical yield of the reduction products ranged from 5 to 90%.