215F07-notes-11-12-07 - Chem 215 F07 Notes — Dr Masato...

Info icon This preview shows pages 1–2. Sign up to view the full content.

Image of page 1

Info icon This preview has intentionally blurred sections. Sign up to view the full version.

Image of page 2
This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: Chem 215 F07 Notes — Dr. Masato Koreeda - Page 1 of 2. Date: November 12, 2007 Carbohydrate stereochemistry More about a- or B- at the anomeric carbon — Taken from: upac/ani‘b/061107.html The anomeric center: The new center of chirality generated by hemiacetal or hemiketal ring closure is called the anomeric center. The two stereoisomers are referred to as anomers, designated or or [3 according to the configurational relationship between the anomeric center and a specified anomeric reference atom. The anomeric reference atom and the anomeric configurational symbol (a or B): The anomeric reference atom is the configurational atom and of the parent, unless multiple configurational prefixes are used. If multiple configurational prefixes are used, the anomeric reference atom is the highest—numbered atom of the group of chiral centers next to the anomeric center that is involved in the heterocyclic ring and specified by a single configurational prefix. In the or anomer, the exocyclic oxygen atom at the anomeric center is formally cis, in the Fischer projection (i.e., the same side with respect to the carbon main chain), to the oxygen attached to the anomeric reference atom; in the [3 anomer these oxygen atoms are formally trans. The anomeric symbol on or followed by a hyphen, is placed immediately before the configurational symbol D or L of the trivial name or of the configurational prefix. D—sugar on! at C—1 (anomeric center) CH20H 1 H O H same side of the ring 8H H anomeric reference I HO OH H OH position a-D—glucopyranose B! at C—1 (anomeric center) CHQOH ¢ H H O OH OH H HO and O on the HO H anomeric reference opposrte Sides of the ring H OH position B—D—glucopyranose L-sugar same side of the ring Q H HO H O OH OH H H H anomeric reference I position H OH a-L-arabinopyranose Chem 215 F07 Notes — Dr. Masato Koreeda — Page 2 of 2. Date: November 12, 2007 Carbohydrate stereochemistry practice examples 1. Draw the OL—pyranose forms and B—furanose forms of each of the following. For pyranose forms draw as a Haworth projection and as a conformational representation (i.e., chair form). fl) 3 CHQOH O=CH CH CH O HO H HO H HO H Ho H HQ H H OH H OH H OH H OH HO H H OH H OH HO H CH20H CH20H CHQOH CH20H H. Draw the open—chain form as a Fischer projection for each of the following. H HOCH 2 H 20H OH OH OH OH OH OH H OH OH OH CHZOH ...
View Full Document

  • Fall '07
  • Koreeda

{[ snackBarMessage ]}

What students are saying

  • Left Quote Icon

    As a current student on this bumpy collegiate pathway, I stumbled upon Course Hero, where I can find study resources for nearly all my courses, get online help from tutors 24/7, and even share my old projects, papers, and lecture notes with other students.

    Student Picture

    Kiran Temple University Fox School of Business ‘17, Course Hero Intern

  • Left Quote Icon

    I cannot even describe how much Course Hero helped me this summer. It’s truly become something I can always rely on and help me. In the end, I was not only able to survive summer classes, but I was able to thrive thanks to Course Hero.

    Student Picture

    Dana University of Pennsylvania ‘17, Course Hero Intern

  • Left Quote Icon

    The ability to access any university’s resources through Course Hero proved invaluable in my case. I was behind on Tulane coursework and actually used UCLA’s materials to help me move forward and get everything together on time.

    Student Picture

    Jill Tulane University ‘16, Course Hero Intern