David Grimes was battening down objects outside his Westport, Conn., home while juggling a deal for a client when the mandatory evacuation order came: Get out of Hurricane Sandy’s way.

His client, Patheon Inc., hoped to nail down its acquisition before the next work week began, so Grimes, a partner in Reed Smith’s New York office, worked with his team through the night, finalizing at 3:30 a.m. the stock-purchase agreement to buy Banner Pharmacaps Inc. for $255 million.