The 17-year-old victim planned to exchange his high-end jacket with the suspect's, but when he entered the subway station about 6 p.m. on Nov. 30, two more men were there too and pulled a knife on him, the NYPD said.
The suspect removed the teen's jacket and the trio fled, police said.
The victim and suspect were "friends" on Facebook, where they had discussed the jacket exchange, the NYPD said.
The Pelle Pelle brand is known for its luxury leather jackets which can cost as much as $1,140.
Anyone with information is asked to call Crime Stoppers at (800) 577-TIPS (8477).