The woman let the teen, Samuel Bell, into her building after she saw him waiting outside to get buzzed in about 11 p.m. July 10, according to the NYPD. She then turned to check her mail, as he hid in the stairwell, police said.
The 41-year-old woman, whose identity was not released, then walked to the building's stairs, where Bell leaped out and grabbed her, demanding that she perform a sexual act on him, police said.
When the woman screamed, Bell snatched her pocketbook, emptied it on the ground and ran off with her wallet and cellphone, cops said.
The woman refused medical attention at the scene.
Bell, who has one prior arrest for petit larceny, was arrested Sunday and was expected to be charged with attempted criminal sex act, assault, robbery and criminal possession of stolen property, police said.