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Carbohydrate-based crown ethers represent a special group of chiral phase transfer catalysts. Several derivatives of these macrocycles have been synthesized in our research group. Among these compounds, monoaza-15-crown-5 lariat ethers proved to be effective phase transfer and enantioselective catalysts in certain reactions. Those chiral azacrown ethers incorporating various carbohydrate moieties in the macrocyclic structure are reviewed, which generated asymmetric induction in reactions, such as Michael addition, epoxidation of enones, Darzens condensation and Michael-initiated ring-closure (MIRC) reaction. Effects on the catalytic activity of the structural changes are the focus.

Enantioenriched, highly functionalized cyclopropane derivatives were prepared by a simple and green approach using monosaccharide-based chiral crown ethers as phase transfer catalysts. The Michael-initiated ring closure (MIRC) reactions of diethyl bromomalonate with 2-cyano-3-phenylacrylate took place with complete diastereoselectivity in the presence of chiral lariat ethers derived from carbohydrates and enantiose-lectivity up to 87 % ee was achieved. Among the catalysts tested, the monoaza-15-crown-5 lariat ether having a methyl βd-glucopyranoside unit and a 2-(3,4-dimethoxyphenyl)ethyl group on the nitrogen generated the highest asymmetric induction (87 % ee). In the reactions of analogous 2-cyano-3arylacrylates, enantioselectivity was in the range of 8-91 % ee.

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