The D312 leaves Shanghai at 7:10pm, and arrives at Beijing South station at 7:07am. Even if it takes 45 mins to get a taxi, you can still make it to financial street or the central business district for a 9am meeting :)

Seriously, though, would you prefer to take a 6:35am plane, or (if it were available) a 4:10am train scheduled to arrive at the same time? Going to bed at 9:30pm in order to leave for the airport at 4:45am isn't terribly disruptive. But taking the train would likely force you to split your night's sleep into two chunks.