4-4 point diagonal attachment, large low corner enclosure
In the 4-4 point diagonal attachment joseki, it is not recommended to play the 4-4 point large low enclosure at . Note that playing at a to form the 4-4 point low enclosure is already not recommended because the resultant position is low. Playing here results in a position that is not only low, but also thin. In most cases, Black should play the one space jump at b instead.
Just as with the 4-4 point diagonal attachment, low corner enclosure, White can play the attachment at followed by entering the 3-3 point with . Either or may consider playing at a.
Black's territory is all gone, and Black is almost left baseless.
The result is similar. The aji at or around a is really bad.
Slarty: What if Black plays here to defend the connection? I can't tell whether is the correct point.