Aldoheptoses have five chiral carbon atoms. What is the maximum possible number of aldoheptose stereoisomers? Draw all of the aldoheptose stereoisomers.

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Everybody. Let's look at our next problem. Aldo heos have four chiral carbon atoms, draw the fissure projections of all the possible stereo isomers of Aldo hexes. So let's record an Aldo heo, we've got six carbons, we have an aldehyde. So we end up with cho, there's our aldehyde at the top C H2O H at the bottom. That's two of them. And so then we have four chiral centers that we indicate with a horizontal bars. We're doing a fisher projection. So we have horizontal bars for each of our chiral centers. So we'll just start with all our hydroxyl groups on those chiral centers on the right side. Now, how many in an tumors are we going to have to draw? Or, or how many stereo isomers? Excuse me, are we going to have to draw, we have a formula for that. So the number of possible stereo isomers is two to the NTH power or N is the number of chiral centers. So we know we have four chiral centers in this molecule. So our possible number will be two to the fourth power is 16. So 16 possible stereo isomers in this case. So we know we'll be done when we hit 16. So the first thing we'll do is draw another version where we just swap at the chiral center at C two. So we're going to take that first hydroxyl group and swap it over to the left. Everything else stays the same. And then what are the naming conventions here? So now we have our first two. The next thing we can do is vary the C three arrangement. So we'll draw to alternate versions that we've just generated but swapping C three. So four chiral centers and we know that we've got the C two, we've got both versions with the C two on either side or rather, I should say the C two hydroxyl group. And now we're going to whoop the three in both of these versions. So we'll put oh on the left side and then just fill out the bottom two as they are hydroxyl on the right. So I'm going to use a little bit of highlighting to show what we've done. So where we swapped C two and then we swapped C three. Actually, I want to use a different color for C three. So I'm going to highlight in yellow where we swap C two, I'll highlight in pink where we swapped C three. So now we want to do the versions where we have swapped C four. So I've redrawn the molecules, the original version and then the version where we swapped the hydroxyl group on carbon two. So you can see we get molecules where we've swapped and put the hydroxyl group on Caron number four. So you can see we've now switched and we'll highlight that green to make it stand out of it. We've now switched on C three, the position of the hydroxide and the hydrogen. And then we have two structures, one with the original structure, except that one switch and one, which is the structure where C two was changed. So just go down here. Now we look at our alternate arrangements and draw our swapped chiral center down one further. As you can see, my handwriting is starting to degenerate as I go further here. So we'll give it its own highlighting color. We will give that a blue color for the ones we swapped there. But now you can see we've got eight different structures here. We've got one more chiral center. We'll generate our sync 16 structures by just varying the position of the last chiral center carbon for each of these molecules. Not going to make you watch me draw it out, but I'll draw it out. We'll put it up and take a quick look. So I drew those final eight here and you get the picture in terms of the pattern I've highlighted in green where we swapped the chiral centers at uh sea five. So I can see it's just versions of all of the various ster isomers previously with that C five carl center swapped. So hopefully that color coding made it a little easier to keep track. But again, we've got Fisher projections of all the possible ster isomers of Aldo hexis. See you in the next video.

Aldoheptoses have five chiral carbon atoms. What is the maximum possible number of aldoheptose stereoisomers? Draw all of the aldoheptose stereoisomers.

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Key Concepts

Chirality

Stereoisomers

Aldoheptose Structure