Horner-Emmons condensation of benzophenone (I) with triethyl phosphonoacetate provides the unsaturated ester (II), which is further reduced with DIBAL in toluene to the allylic alcohol (III). Reaction of alcohol (III) with methanesulfonyl chloride and Et3N leads to chloride (IV). Finally, alkylation of 3-propionyl-3,9-diazabicyclo[3.3.1]nonane (V) with the allyl chloride (IV) furnishes the title compound.