Ring structure for ketopentoses

[pegasus10]

Hello, is it possible to draw the ring structure of a ketopentose, like for example D-ribulose? I've been browsing the web and some organic chemistry textbooks, but I haven't been able to find anything.

Thanks in advance!

Edited November 19, 2018 by pegasus10

[chenbeier]

Maybe this:

 

https://www.google.com/search?q=ketopentose+ringform&client=firefox-b&tbm=isch&source=iu&ictx=1&fir=-v76lGvCZRYPvM%3A%2CBx9t22rEqeKo4M%2C_&usg=AI4_-kRdF7ma8ygSKaqu772wrqjAcUGfMQ&sa=X&ved=2ahUKEwihgYq9juHeAhWhw4sKHdtUCi4Q9QEwA3oECAAQCg#imgrc=-v76lGvCZRYPvM:

[BabcockHall]

Use the hydroxyl group at carbon-5 to form the hemiacetal.  https://commons.wikimedia.org/wiki/File:D-Ribulose_Haworth.svg

[BabcockHall]

On 11/24/2018 at 9:21 AM, BabcockHall said:

Use the hydroxyl group at carbon-5 to form the hemiacetal.  https://commons.wikimedia.org/wiki/File:D-Ribulose_Haworth.svg

That should read hemiketal, not hemiacetal.

Edited November 26, 2018 by BabcockHall