Rosewood Realty Group has successfully brokered the sale of a six-story elevator apartment building at 748 St. Marks Ave. for $3 million. The sale price represents 7.7 times the current rent roll, according to Aaron Jungreis, Rosewood Realty Group founder and president, who brokered the deal. The building, consisting of 36 apartments, is located in the Crown Heights neighborhood. "The property has tremendous upside potential in this changing neighborhood with solid housing stock, transportation options and tree-lined blocks," Jungreis said. Jungreis founded Rosewood Realty Group in 2007 and specializes in multi-family residential buildings and office buildings, with activity focused in New York, New Jersey, Connecticut and Florida.