Ribose cyclization: pyrane or furane?

[Aymeric]

Main Question or Discussion Point

Hello,

My biochemistry textbook tells me that ribose and fructose give furanes. I had trouble wrapping my head around the cyclization process so I looked for other explanations and I found this one:
http://web.campbell.edu/faculty/nemecz/323_lect/sugars/cyclization.html [Broken]

It seems to say that ribose can take on two forms : furane or pyrane. I just wanted confirmation that linear ribose becomes a furane or a pyrane depending on which -OH connects back to the aldehyde function (if it connects to the last one, it becomes ribopyranose, if it connects to the one before last, it becomes ribofuranose).

Did I get this right?

Thanks!

 

[chemisttree]

Sounds right to me. Intramolecular aldol condensation.

edit: But you will get both the alpha and beta anomer for both of these cyclic forms depending upon which 'face' of the aldehyde the OH approaches.