49ers QB Brock Purdy, Demarcus Robinson building chemistry at training camp

SANTA CLARA — Quarterback Brock Purdy aired it out on Thursday, and he did not come up short.Purdy connected with veteran wide receiver Demarcus Robinson for the play of the day. Purdy heaved a deep ball to Robinson, who beat the coverage of cornerback Darrell Luter and hauled in the pass 45 yards down the field.“Brock, when he gets the look and it’s there, he rarely misses it,” 49ers coach Kyle Shanahan said. “I’ve been happy with him. He got a few opportunities that he’s come up short on, but he got a good one today and he’s had a few throughout camp.”Robinson, Russell Gage and rookie Jordan Watkins have been the 49ers’ top wide receivers during practices this summer as the team has been shorthanded due to injuries.There is no timetable for Brandon Aiyuk’s return from ACL surgery. And Jauan Jennings is out indefinitely with a calf injury that he aggravated during practice on Sunday.The 49ers are being cautious with Ricky Pearsall, who is coming back from a hamstring condition.The team is also battling a depth problem at cornerback.The...