Not with a non-AoE melee attack. All range, even range 1 melee attacks, can't be counted through walls. In fact, for all intents and purposes (including looting), these two hexes are not adjacent and considered two hexes apart. Note that AoE Melee attacks use their diagram (not adjancency) to determine if a target is in range. The following image shows the range (4 red hexes) between a source and a target. The blue line shows their LOS.