Officers from District 1 patrolling in the Boston Common area this morning at about 12:58am observed a male committing a sex act alone in a doorway at about 100 Boylston Street. Officers identified themselves and the suspect began to flee the area. The suspect was eventually stopped at about 80 Boylston Street and placed under arrest. Anthony Jones, 44, of Dorchester was charged with Lewd and Lascivious Behavior, Disorderly Conduct and additionally charged with Failing to Register as a Sex Offender when officers discovered through a record check he had not registered.Jones will be arraigned in the Boston Municipal Court on Monday morning.