Study recommended for 22 kyu or stronger.(Show more of this level)
The move of 1 is a sequence that ends in gote. Because it is gote, black should only play this move when he already has a stone around 6. In that case this sequence is actually a joseki.
However in this case black does not have a stone in that area, and white is most likely to play there, to ruin his plans (as seen in the diagram). This brings black at a disadvantage.