| 摘要 |
A first method comprises: i).Reacting 2-bromo-2-butene with magnesium in a non-interfering solvent, wherein a first reaction mixture containing 2-butene magnesium bromide, magnesium and the non-interfering solvent is produced; and ii).Adding an alkyl formate of formula H-C(=O)(R) (where R is C1-C4 alkyl) to the first reaction mixture, where the alkyl formate reacts with the 2-butene magnesium bromide in the first reaction mixture to produce a second reaction mixture containing a compound of the formula shown; and iii).Adding an aqueous acid of formula R1-C(=O)(OH) wherein R1 is a one to five carbon alkyl group to the second reaction mixture, wherein a third reaction mixture containing 3,5-dimethyl-2,5-heptadiene-4-ol in the solvent is produced. The above first method may optionally further comprise the following steps: iv).Removing the solvent from the third reaction mixture, wherein solvent-free 3,5-dimethyl-2,5-heptadiene-4-ol is produced; and v).Treating the solvent-free 3,5-dimethyl-2,5-heptadiene-4-ol with hydrochloric acid, wherein a fourth reaction mixture containing 3-methyl-2,5-cyclopentadiene is produced. Also described is a second method, which comprises: i).Reacting 2-bromo-2-butene with magnesium wherein the reacting occurs in the presence of from 1% to 10% stoichiometric excess of magnesium and in the presence of THF at a temperature of 40oC to 50oC, and wherein a first reaction mixture containing 2-butene magnesium bromide, magnesium and THF is produced; and ii).Adding ethyl formate to the first reaction mixture at a temperature of -10oC to 10oC where the ethyl formate reacts with the 2-butene magnesium bromide in the first reaction mixture to produce a second reaction mixture containing a compound of the formula shown; and iii).Adding an aqueous acetic acid to the second reaction mixture, wherein a third reaction mixture containing 3,5-dimethyl-2,5-heptadiene-4-ol, THF and magnesium acetate is produced. The second method may optionally further comprise the following steps: iv).Removing THF from the third reaction mixture, wherein THF-free 3,5-dimethyl-2,5-heptadiene-4-ol is produced; and v).Treating the THF-free 3,5-dimethyl-2,5-heptadiene-4-ol with aqueous hydrochloric acid, and ethyl ether wherein a fourth reaction mixture containing chlorotetramethylcyclopentene, tetramethylcyclopentadiene and ethyl ether is produced.
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