A Novel Process For Stereoselective Synthesis Of α-Asarone

α-Asarone is the effective ingredient taked out from Acorus gramineus soland. The author has found thatα-Asarone is very useful in different fields after reading a number of literatures. Internal and overseas scientists have studied onα-Asarone in the early 1960s. It is found thatα-Asarone play an essential role in relieving a cough, removing the phlegm, calmless, resisting convulsion. Because Chinese traditional medicine is limited, studies on stereoselective synthesis ofα-Asarone have been paid more and more attention to. This paper will study the condition of stereoselective synthesis ofα-Asarone.2, 4, 5-trimethoxybenzaldehyde was synthesized from 1, 2, 4-trimethoxybenzene by the Vilsmeier reaction. First, synthesis ofα-Asarone by Wittig reaction was studied, the result showed that the yield and stereoselectivity to synthesizeα-Asarone is lower. Then synthesis ofα-Asarone by Grignard reaction was studied. The intermediate aromatic alcohol was prepared by the reaction of magnesium ethyl bromide with 2,4,5-trimethoxybenzaldehyde, the catalysis of different dehydrant was evaluated for the yield and stereoselectivity to synthesizeα-Asarone. The results showed thatα-Asarone was stereoselectively obtained with dominant E-stereoselectivity(93.3%) under catalysis of cupric sulfate in dry toluene, the yield was 80.2 % (based on the aromatic aldehyde).From the synthetic route ofα-Asarone, a fewβ-Asarone will be maked withα-Asarone.β-Asarone whose structure likeα-Asarone has strong toxicity. The content ofβ-Asarone shouldn't achieve 1% according to the requirement of Chinese pharmacopoeia (2000). The content ofα-Asarone was mensurated by the method of HPLC and GC. Comparing the two methods GC is more simple and convenient than HPLC. The result showed that the content ofα-Asarone reached the requirement of pharmacopoeia.A new simple and efficient proces for the industrial production ofα-Asarone was provided.