HFF has arranged $55 million in first mortgage financing at 185 Dartmouth St. in Boston for Synergy Investments.

HSBC Bank provided a long-term, fixed-rate loan that was used to pay off debt, provide capital and return equity upon stabilization.

185 Dartmouth St. is a 164,559-square-foot Class A office and retail building across from the MBTA’s Back Bay station. The Art Deco structure built in 1937 contains eight floors of boutique office space, ground-floor retail and a Healthworks fitness center. Tenants include Denham Capital, First American Title, Boston Athletic Association, Starbucks, Freshii and FedEx Kinkos.

HFF’s Greg LaBine and Patrick McAneny led the HFF debt placement team.

“HSBC Bank provided a flexible financing alternative for this transaction, with pricing reductions over time as the project achieves various milestones on its way to stabilization,” LaBine said in a statement.