Midtown-based real estate investment banking firm DTZ Rockwood, which provided advisory services for the purchase of the troubled Apthorp apartment building, filed for Chapter 11 bankruptcy protection yesterday in Manhattan federal court. The firm claimed it owes between 50 and 99 creditors’ debts of $79 million and assets of $1.8 million, according to bankruptcy court filings entered yesterday. DTZ Rockwood provided advisory services for Mann Realty Associates’ $426 million purchase of the 136-unit luxury rental building Apthorp, at 390 West End Avenue, in 2007. The building is now being converted to residential condominiums, and is beset by lawsuits. [more]