D and L orientation

[BenZq]

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I'm having a bit of trouble solving for D and L orientation on cyclic sugars. Is the general rule that if the last Chiral Carbon (which is attached to the -OR group) has an R orientation then its D, and S corresponds with L? Any help would be much appreciated.

PS. I get that Up corresponds with D, but I'm trying to understand problems with rings such as

 

[BerkReviewTeach]

I'm having a bit of trouble solving for D and L orientation on cyclic sugars. Is the general rule that if the last Chiral Carbon (which is attached to the -OR group) has an R orientation then its D, and S corresponds with L? Any help would be much appreciated.

PS. I get that Up corresponds with D, but I'm trying to understand problems with rings such as

If it were a pyranose ring, then you could use the up=D rule. But in the furanose ring you've drawn, the fifth carbon is not part of the ring. You need to look at carbon 5 in its Fisher projection (which is shown) and determine whether it's R or S. For that sugar, if it's R, then it's a D-sugar. If it's S, then it's an L-sugar.

I get that it's S at carbon-5.

#1 is OH, and it's on the right
#2 is the furnaose ring, and it's down
#3 is the CH2OH group, and it's up
#4 is H, and it's on the left (and therefore pointing out in the Fisher projection)​

The 1-2-3 circle is clockwise, but because H (#4) is in front, the chirality is actually S. S equates to L in this specific case, so I'd pick L.

 

[BenZq]

Thanks that really helps