The reaction of octaethylporphyrin (I) with 3-(dimethylamino)acrolein (II) by means of POCl3 gives the 10-(2-formylvinyl)octaethylporphyrin (III), which is treated with decylmagnesium bromide (IV) in THF to yield the corresponding alcohol (V). The cyclization of (V) in concentrated H2SO4 affords the decylbenzochlorin (VI), which is finally treated with zinc acetate in methanol/dichloromethane to provide the target zinc complex.