Ken Rosenthal, who opened a bakery café near St. Louis, with sourdough bread as its star, and built it into a small chain that would become Panera Bread, died on Feb. 14 at his home in Scottsdale, AZ. He was 81.

Mr. Rosenthal’s detour from selling women’s dresses to selling baked goods proved a smart one. From 1987 to 1993, he and his three partners expanded the first café into a chain of 20 stores in Missouri and Atlanta. In 1995, the cafés were bought by Au Bon Pain, which changed the corporate name to Panera Bread. Panera currently has 2,230 restaurants in the United States.

Mr. Rosenthal explained his operating style when he talked to The Post-Dispatch in 1997. “I’ve always been best when I’m completely challenged,” he said. “When things get to be routine with me, I suppose I lose a little interest. I’m not a great operator. I’m a better pioneer than I am anything else.”