If you specifically want a new cmd window with that specific title, from which your program is run, you may try the following:
start "dBox" cmd | "c:\program files (x86)\dropbox\client\dropbox.exe"
start "dBox" cmd | (start /d "c:\program files (x86)\dropbox\client" dropbox.exe)
I don't have DropBox installed, but this works for other executables, so it should work for you.
Walking through the code, what you want first of all is a new command window, and running the DropBox executable is subsequent to that, so let's at least see how to get a new cmd window with your title going: start "dBox" cmd
Now, how do we repeat that while also getting another executable to run from that window? This is where the "|" (pipe) symbol comes into play, which is for redirection. The documentation says that the output from the command on the left is piped into the command on the right. We want a new process started from a new cmd window, and the only way I've been able to get that to work (seemingly so, anyway) is by using start
twice.
You can read more about redirection here.
Edit:
The first command is crossed out because I realized it made the process a child of the original cmd window. The giveaway is that the original cmd window is unusable until the child process is killed. I can't confirm, at the moment, if the second command does the trick exactly as stated in the question.