The new synthesis of 10-bromo-α-chamigrene was achieved as follows;6-methyl-5-heptene-2-one was transformed into corresponding thioacetals,and then successively treated with Cp_2Ti(P(OEt)_3)_2.The intermediate reacted with mono-ketal of cyclohexane-1,4-dione,and gave the carbonyl coupling product.It was then transformed into the key intermediateγ-bisabolene via deketalization,Grignard reaction,dehydration and then furnished the target molecule by polyene cyclization,with total yield 2%. All structures were confirmed by ~1H NMR and ~(13)C NMR.The final compound was confirmed by ~1H NMR,~(13)C NMR and MS. The new synthesis of 10-bromo-α-chamigrene was achieved as follows; 6-methyl-5-heptene-2-one was transformed into thioacetals, and successively successively treated with Cp_2Ti (P (OEt) _3) _2.the intermediate reacted with mono-ketal of cyclohexane-1,4-dione, and gave the carbonyl coupling product. It was then transformed into the key intermediate γ-bisabolene via deketalization, Grignard reaction, dehydration and then furnished the target molecule by polyene cyclization, with total Yield 2%. All structures were confirmed by ~ 1H NMR and ~ (13) C NMR. The final compound was confirmed by ~ 1H NMR, ~ (13) C NMR and MS.