Double Michael Addition in the synthesis of α-2-Deoxy-Ulosides from β-enamino Ketone
碩士 === 中國醫藥大學 === 藥物化學研究所碩士班 === 101 === Hex-1-en-3-one that had been prepared by oxidation reactions of D-glucals or D-galactals were subjected to Michael addition15 with 3.0 equiv of primary amines (including benzylamine, n-butylamine, and n-octylamine) in MeOH for 2 h. The products,β-Enamino keto...
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| Format: | Others |
| Language: | zh-TW |
| Published: |
2012
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| Online Access: | http://ndltd.ncl.edu.tw/handle/92471348350965285743 |
| Summary: | 碩士 === 中國醫藥大學 === 藥物化學研究所碩士班 === 101 === Hex-1-en-3-one that had been prepared by oxidation reactions of D-glucals or D-galactals were subjected to Michael addition15 with 3.0 equiv of primary amines (including benzylamine, n-butylamine, and n-octylamine) in MeOH for 2 h. The products,β-Enamino ketone 26, were obtained in 87-95% with high diastereoselective Z-geometry due to the intramolecular hydrogen bonding.
β-Enamino kentone 26a reacted with n-hexanol under basic conditions. Several Lewis acids (3.0 equiv), solvents and temperatures were examined. Among these reaction shown that 12N HCl (3.0 equiv) at 100 W/60 oC for 10 min was found to provide the desired product n-hexyl-2-deoxy-α-deoxyulosides (27) with the highest isolated yield (88%) and stereoselectivity (ratio of α/β-amomers: 95/5).
α-2-Deoxyglycosides were synthesized in good yields by microware-assisted reaction of β-enamino ketone with various O- and S-nucleophiles in the presence of 3.0 equiv of hydrogen chloride. These glycosyl additions were throgh the double Michael reaction and occurred high α-stereoselectivity and were complete in 10 min in 51-93% yield.
The palladium complex were synthesized in good yields by reacting β-enamino ketone with palladium(II) acetate in the presence of 5.0 equiv of sodium bicarbonate and 1.0 equiv of tetrabutylamino bromide in DMF at room temperature for 3 h.
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