The invention relates to a method for synthesizing
Varenicline intermediate 2, 3, 4, 5-
tetralin-1, 5-
methylene-
hydrogen-benzoazepine. The method includes the following steps: under the action of catalyst, mixing amyl
nitrite with o-
aminobenzoic acid solution to generate diazonium salt, then mixing the diazonium salt with
cyclopentadiene, and heating to react to generate compound 1; feeding
ozone into the solution of compound 1, after complete conversion, adding
reducing agent to generate compound 2, then dripping the compound 2 to the
mixed solution of triacetoxy
sodium borohydride and
benzylamine to generate compound 3 by
loop closing; and hydrogenating the compound 3 under the action of
palladium and carbon for debenzylation and reduction to obtain M intermediate 2, 3, 4, 5-
tetralin-1, 5-
methylene-
hydrogen-benzoazepine. The method has the advantages of greatly simplifying the method for preparing
Varenicline intermediate, being simple in production process and safe in operation, well ensuring no harm to the environment and control on production cost, increasing yield and being capable of becoming a process in great industrial production.