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I'm confused about the structure...doesn't L mean the OH or the phosphate should be on the left side?
Another way to think of this is to remember that usually the D configuration is pretty much the R configuration for the penultimate C whereas L is pretty much the S configuration - granted, D/L and R/S are completely separate systems (D/L refers to direction of rotation of polarized light while R/S is the physical organization of atoms around the chiral center), but this is still a good rule of thumb to keep in mind.
The rule-of-thumb saying D is right and L is left only works when the group above the chiral C in question is higher priority than the group below. For example, in glucose the above group is a 4-carbon chain while the group below is a mere CH2OH unit.
In this case, the phosphated group below is higher priority; so rotate the molecule 180 degrees in the plane of page to figure out the correct config.
Another way to think of this is to remember that usually the D configuration is pretty much the R configuration for the penultimate C whereas L is pretty much the S configuration - granted, D/L and R/S are completely separate systems (D/L refers to direction of rotation of polarized light while R/S is the physical organization of atoms around the chiral center), but this is still a good rule of thumb to keep in mind.