He didn’t. The objective of the 1942 offensives wasn’t Stalingrad, which was on the flank of the drive into the Caucasus to obtain control of the oil fields there. While being a side offensive, Stalingrad proved harder to take than expected. read more
This is why Case Blue happened (Stalingrad) As far as I know, some generals argued that it was more important to destroy Red Army, and so attacking in the Center (Moscow) was a must, but Hitler believed he was a genious. read more
Moscow was the capital of USSR and capital of Russia today. read more