Chicago-based Katten Muchin Rosenman LLP has opened an office in Costa Mesa with longtime Orange County lawyer Craig Barbarosh as managing partner.

Barbarosh had been the managing partner of the local office of San Francisco-based Pillsbury Winthrop Shaw Pittman LLP.

Pillsbury Winthrop closed its office here earlier this week, when its last five lawyers joined Katten. Pillsbury had been struggling for several years to keep lawyers and grow in the increasingly competitive legal market here.

“I think what Pillsbury would say was that OC was not a strategic location for them,” Barbarosh said. “Katten has a lot of client relationships in OC already. Now that I’m here, we’ll build this office in a way that’s strategic.”

Barbarosh focuses on financial restructuring and insolvency. He sits on the boards of Quality Systems Inc. and Sabra Health Care REIT Inc., both in Irvine.

He also has joined Katten’s board.

Katten’s new office takes the space formerly occupied by Pillsbury in Costa Mesa. Barbarosh is the only attorney here so far.

Three other partners, Bill Freeman, Jan Cate and Brad Wolf, are expected to open a second office in Los Angeles in coming weeks. Karen Dine is a partner based in New York.