Italian real estate and financial firm Sorgente Group is the latest among a series of international investors eyeing Manhattan office buildings. Sorgente CEO Valter Mainetti told Bloomberg that his group is in talks to purchase a 51 percent stake in the 57-story Woolworth Building at 233 Broadway in the Financial District. Sorgente, which is also invested in the Flatiron Building, is reportedly in talks to invest in two other New York City buildings, but Mainetti said he could not disclose what they were.