Application of 4,5-methylene-L-proline as catalyst in direct asymmetric Aldol reaction
A proline, methylene technology, applied in physical/chemical process catalyst, organic compound/hydride/coordination complex catalyst, carbon-based compound preparation and other directions, can solve the problem of low catalytic efficiency, low product yield, The problem of large amount of catalyst is to achieve the effect of high catalytic efficiency, high yield and large-scale production.
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Embodiment 1
[0031] In this example, acetone and p-nitrobenzaldehyde are used as substrates, and trans-4,5-methylene-L-proline (I), cis-4,5-methylene-L-proline The activity of direct asymmetric Aldol reaction catalyzed by amino acid (Ⅱ) and L-proline was confirmed.
[0032] Experimental method: Add 4,5-methylene-L-proline catalyst or L-proline catalyst (0.15mmol), DMF (1mL) and acetone (2.5mmol) into the reactor, drop p-Nitrobenzaldehyde (0.5mmol), TLC tracking to the complete consumption of reaction raw materials, after the completion of the reaction, add saturated NH 4 Cl solution, extracted with ethyl acetate, anhydrous Na 2 SO 4 Dry, filter, remove the solvent under reduced pressure, and separate by thin layer chromatography (ethyl acetate / n-hexane is the developing solvent) acetone and Aldol products of p-nitrobenzaldehyde. The enantiomeric excess (ee value) was determined by chiral high pressure liquid chromatography analysis of the pure product.
[0033] The results are shown in...
Embodiment 2
[0038] In this example, using acetone and p-nitrobenzaldehyde as substrates, the amount of catalyst and different additives in the direct asymmetric Aldol reaction catalyzed by trans-4,5-methylene-L-proline (I) system research.
[0039] Experimental method: Add 4,5-methylene-L-proline catalyst (0.15mmol), DMF (1mL), additives and acetone (2.5mmol) into the reactor, add p-nitrobenzaldehyde dropwise at 0°C (0.5mmol), TLC traces to the complete consumption of reaction raw materials, after the completion of the reaction, add saturated NH 4 Cl solution, extracted with ethyl acetate, anhydrous Na 2 SO 4 Dry, filter, remove the solvent under reduced pressure, and separate by thin layer chromatography (ethyl acetate / n-hexane is the developing solvent) acetone and Aldol products of p-nitrobenzaldehyde. The enantiomeric excess (ee value) was determined by chiral high pressure liquid chromatography analysis of the pure product.
[0040] The results are shown in Table 2. It can be see...
Embodiment 3
[0046] This embodiment uses acetone and p-nitrobenzaldehyde as substrates, referring to the experimental method of Example 2, for the direct asymmetric Aldol reaction catalyzed by trans-4,5-methylene-L-proline (I) The main influencing factors such as solvent, reaction temperature and reaction time were systematically studied.
[0047] The results are shown in Table 3. It can be seen that when the solvent is DMF and the reaction temperature is -20°C, the yield and enantioselectivity are higher.
[0048]
[0049] Table 3 Effect of solvent and temperature on the direct asymmetric Aldol reaction catalyzed by trans-4,5-methylene-L-proline (Ⅰ)
[0050]
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