More than 300 persons turned out recently to place deposits on condominium apartments and town houses being sold in the formor Claremont Community complex in Arlington, the Klingbeil Management Group Co. reported. The 518-unit complex on South Walted Reed Drive nrar Rte. 7 -- renamed The Arlington -- is being converted from rental to condominium ownership. Prices ramge from $44,900 to $69,990. The redeveloper is Claremint Apartments Ltd. The Anden Group is the general contractor.

Previews Inc. reported that it has taken over the premises of the former Middleburg, Va., office of Sotheby Parke Bernet's real estate group. Leffert Lefferts and Jane Williams, both formerly with Sotheby, are in the new Previews' office. An international real estate marketing organization that formerly had an office in downtown Washington, Previews has nine other offices in the country.

Wintergreen, a 13,000-acre resort community in the Blue Ridge Mountains 50 miles southwest of Charlottesville, Va., has announced plans to build a $2.8 million multi-purpose conference and retail center. Lewis F. Payne, Wintergreen president, said the Mountain Inn will have conference, shopping, dining and lodging facilities. Completion is scheduled late in 1980.

New England Components/Techbuilt, manufacturers of custom houses in North Dartmouth, Mass., has opened an office at 6801 Whittier Ave., McLean. Margaret Leaf is vice president in charge of sales.

A seminar on energy efficiency devices used in home building will be held from 10 a.m. to 3 p.m. Thursday at 8012 Old Alexander Ferry Rd., Clinton, Md. Ira Kaufman, sponsor, said that builders and contractors are welcome. For information, call 868-0300.

Hugh T. Peck Properties Inc. has opened a full-service insurance division office in Wheaton. Headed by Al Pisani, a veteran realty broker, the office will operate independently of Peck's 22 real estate sales offices.

The Bakery, Confectionary & Tobacco Workers International Union plans to occupy a four-story building under construction at Connecticut Avenue and Warner Street in Kensington in the summer of 1980.

Walker & Dunlop recently arranged the land sale leaseback of the 88,000-square-foot Control Data Building at 1455 Research Blvd., Rockville, to Research Park Associates. Total financing for the 15-year-old property was $3.1 million.

Holland & Lyons Associates Inc., realtors, has opened an office at 10000 Falls Rd., Potomac. It is the District-based firm's first office in Montgomery County. Betty Clarke is the administrative director of the new office.

Montgomery College and the Montgomery County Board of Realtors will so-sponsor a real estate career day from 1 to 3 p.m. next Saturday at the Rockville campus. The public is invited. For information, call 279-5241.