Synthesis Of Chiral Ionic Liquid-supported Macmillan Catalyst And Application In Enantioelective Diels-aider Reaction

Chirality is the basic attributes of nature, the role of the different configurations of chiral molecules in life are also different. Recently asymmetric synthesis became one of the most important strategies for synthesis of chiral compounds. This paper we wish to report our recent work on the synthesis of a new chiral ionic liquid-supported MacMillan catalyst and its organocatalytic enantioselective Diels-Alder reactions. Especially noteworthy, the catalysts I could be easily recovered and reused without remarkable decrease in yields and enantioselectivities.L-tyrosine as raw material by esterification, amino protection, "Click" reaction, quaternary ammonium, amine solution and cyclization synthesized three kinds of chi-ral ionic liquid-supported MacMillan catalyst. All intermediates and catalysts were c-haracterized by 1HNMR spectroscopy, elemental analysis, Polarimeter and TGA. The result of TGA indicated that thermal stability of chiral ionic liquid-supported MacMillan catalysts are up to 323 ℃. Chiral ionic liquid that contained 1,2,3-triazo-lium have a higher thermal stability. These catalysts could be used as chiral organoca-talysts for asymmetric Diels-Alder reactions with good yield and enantioselectivity. After screening the different solvent, co-catalyst acid and the loading of catalyst, we find the optimized reaction conditions for the asymmetric Diels-Alder reaction of trans-cinnamic aldehyde and cyclopentadiene by utilizing 10 mol% of catalyst I,10 mol% of CF3COOH as the acidic co-catalyst, and CH3OH/[BMIM]BF4/H2O(v/v/v, 50/45/5)as the reaction solvent, at room temperature. Under this condition, whether it is an electron-withdrawing or electron-donating group substituted α,β-unsaturated aldehyde can obtain the corresponding product of the cycloaddition reaction with cyc-lopentadiene in moderate to good yields (78% -97.6%) with good to excellent enanti-oselectivities. After completion of the reaction, catalyst I was recovered by simple ex-traction, dried for 6 h at 65 ℃ under high vacuum, and reused in the next reaction after activation withTFA. The catalyst I can be recovered and recycled for up to eight runs with no loss of enantioselectivity and yield.