Planning is underway to convert a historic office building in downtown Minneapolis into apartments aimed at workers in the city's central business district.

Developer Todd Phillips said Friday that he plans to buy the 260,000-square-foot Plymouth Building, where he will create 252 market-rate units as well as two restaurants. He declined to discuss the terms of the deal but said the sale is expected to close this summer.

"Part of the secret to this deal is that it's skyway-connected," said Phillips, managing director of Minneapolis-based TruCore Realty.

The project is the latest in a long list of proposals to create thousands of new apartments in both new and existing buildings as developers take advantage of historically low apartment vacancy rates in the city. Phillips said he has a meeting with the neighborhood group next week and the property must be rezoned. He's seeking financial assistance for asbestos and lead-paint abatement, and expects to receive up to $12 million in state and federal historic tax credits.

Mary Bujold, president of Maxfield Research Group, said that in downtown Minneapolis and just across the Mississippi River, 2,100 apartments are under construction. At 2.2 percent, apartment vacancy rates in downtown Minneapolis are among the lowest in the city. In Class B and C office buildings like the Plymouth Building, vacancy rates are more than 20 percent, making them ideal targets for conversions into other uses. "A lot of these old office buildings have been languishing," she said.

Phillips said that the building is only about half full. The deal also includes the purchase of two smaller adjacent office buildings. The seller is a company led by Gerry Cafesjian, a former executive with West Publishing, which bought the building about a decade ago.

The 12-story Plymouth Building dominates the corner of 6th Street and Hennepin Avenue and is sandwiched between high-rise office buildings and a burgeoning "cultural corridor." It has a three-way skyway connection to nearby buildings, including one that houses thousands of Target employees. The building is also situated near the light-rail transit stop.

When built in 1910, the Plymouth Building was known as one of the largest reinforced all-concrete office buildings in the country. Recently, the main floor of the building was home to Wondrous Azian Kitchen, which has since closed. Phillips said that he plans to convert that space into two restaurants. Other first-floor tenants, including a hair salon and Lyon's Pub, will remain.

Phillips was involved with the recent conversion of the 430 Oak Grove building in the Loring Park neighborhood into upscale apartments. That project was led by Kraus-Anderson, which will serve as a contractor on the Plymouth Building. Phillips said he's planning to make 75 percent of the 252 units one-bedroom apartments with about 500 square feet. Rents will range from about $1,200 to $1,400, with occupancy anticipated in late 2014.

Jim Buchta • 612-673-7376