Synthesis method of dextromethorphan

The invention provides a method for synthesizing dextromethorphan, which comprises the following steps: by taking 2-(2-oxocyclohexyl) acetonitrile as a raw material, carrying out Robinson cyclization reaction to generate a compound 2; performing aromatization reaction on the compound 2 to generate a compound 3; carrying out keto-carbonyl reduction reaction on the compound 3 to generate a compound 4; performing cyano reduction on the compound 4 to generate a compound 5; performing cyclization reaction on the compound 5 to obtain a compound 6; performing asymmetric catalytic hydrogenation on the compound 6 to obtain a compound 7; the compound 7 is subjected to an N-methylation reaction, and dextromethorphan is obtained. The invention develops a new asymmetric synthesis route for preparing dextromethorphan, avoids intermediate resolution, improves the yield, improves the atom economy and reduces waste. 本发明提供了一种右美沙芬的合成方法，以2-(2-氧代环己基)乙腈为原料，经过Robinson成环反应，生成化合物2；化合物2经过芳构化反应，生成化合物3；化合物3经过酮羰基还原反应，生成化合物4；化合物4经过氰基还原，生成