Real estate firms rich in cash have snatched up the most high-profile office towers on the market in Manhattan this year, while highly-leveraged players have been sidelined. Shorenstein Properties bought two of the seven office buildings that Harry Macklowe needed to unload, the Park Avenue Tower at 65 East 55th Street and 850 Third Avenue. Shorenstein, based in San Francisco, had never bought a New York City property until 2003. Just 44 Manhattan towers have been sold this year, down 57 percent from last year, according to Real Capital Analytics. Other newly active buyers include investor Lloyd Goldman and a joint venture between L&L Holding Co. and Prudential Real Estate Investors.