A group of men, who were mainly wearing hooded tops and dark clothing, approached the victim around 7.50am on Saturday (October 24) and asked if he wanted to buy drugs.
When he declined they walked him to a cash machine in Second Avenue and threatened him with violence if he did not buy them goods from the local store. He did so and they left.
Police received a subsequent report where the victim was allegedly sexually assaulted by touching, on Old Shoreham Road, Hove.
A number of men were detained by police officers at Hove railway station. Four were arrested at nearby locations.
Louis Mason-Powell, 22 of Marvels Lane in Lewisham, was charged with assault of a person thereby causing actual bodily harm and two counts of theft.
Tobi Adediwura, 19, of no fixed address, was charged with assault of a person thereby causing actual bodily harm.
Rasean Robinson, 19, of Ravensmead Road in Bromley, was charged with robbery, sexual assault and possession of a Class B drug.
They have been remanded in custody to appear before Brighton Magistrates’ Court on Monday (26 October).
A fourth suspect, a man aged 19, was arrested and bailed subject to strict conditions.
Police continue to appeal to anyone who was in the area at the time of these incidents to come forward and speak to officers.
Anyone with information can report online or call 101, quoting 258 of 24/10.