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This thesis by Sharpless asymmetric epoxidation of producing optically active 3 - (methylthio) hexanal, 5 (6) - butyl-1, 4 - dioxan -2 - one and 2 - methyl-3 - mercapto pentyl aldehyde. As a starting material to (E) -2 - hexenal by aldehyde reduction of Sharpless asymmetric epoxidation to restore an epoxy ring, nucleophilic substitution, Swern oxidation reaction of the optically active 3 - (methylthio) hexanal. In addition to the Sharpless asymmetric epoxidation reaction yield is slightly lower, at around 65%, the other step of the synthesis route reaction yields were about 75%. (E) -2 - hexenol Sharpless asymmetric epoxidation reaction conditions were optimized, the optimum reaction conditions for the reaction temperature of-25oC, Ti (Oi-Pr) 4 dosage 10% (with (E) -2 - Hexenyl molar ratio), the t-BuOOH and (E) -2 - hexenol molar ratio is 2:1, and the optically active 2, 3 - epoxy-hexyl alcohol in about 65% yield of the reaction ee value of about 93%. The optically active 2, 3 - epoxy hexanol After DIBAL-H region selectively reduced to give the optically active 1, 2 - hexanediol, yield about 72%. Α-bromo-acetic acid chloride to obtain optically active 5 (6) - butyl-1, 4 - dioxan -2 - one, 6 - butyl-1, 4 - dioxan-2 - one as the main The product with 5 - butyl-1, 4 - dioxan-2 - ketone ratio of about 4/1, the total yield of the two products is about 71% or so. Optically active product, 3 - (methylthio) hexyl aldehyde, and 5 (6) - butyl-1, 4 - dioxane-2 - one The ee value was determined by chiral GC measurement. (S) -3 - methylthio-hexanal ee value of 90.8%, (R) -3 - methylthio-hexanal ee value of 91.1%; (R) - and (S) -5 (6) - butyl-1, 4 - dioxane-2 - keto ee values ??are about 90%. By Sharpless asymmetric epoxidation reaction to prepare an optically active 3 - (methylthio) hexyl aldehyde, and 5 (6) - butyl-1, 4 - dioxan -2 - ketone, chemical yield of each step and the objective product EE values ??are high, so is ideal preparation of optically active 3 - (methylthio) hexyl aldehyde, and 5 (6) - butyl-1, 4 - dioxan-2 - the asymmetric synthesis of the ketone. This paper attempts through similar to the optically active 3 - methylthio hexanal preparation method, the synthesis of 2 - methyl -3 - mercapto-valeraldehyde. With 2 - methyl-pentenoic acid as a starting material by a carboxyl group, reduction and Sharpless asymmetric epoxidation to obtain optically active 2 - methyl-2, 3 - epoxy pentanol. But 2 - methyl-2, 3 - epoxy-pentanol by the Red-Al reduction received only the 1, 2 - diol, rather than the required 1, 3 - diol, therefore not to give 2 - methyl -3 - mercapto-valeraldehyde. The preparation of optically active 2 - methyl-3 - mercapto-valeraldehyde needs further exploration and research.
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