Sciencemadness Discussion Board

Defining stereochemical terms - pseudo and allo

ziqquratu - 24-2-2013 at 01:40

Greetings all,

"Pseudo" and "allo" seem to be somewhat common (if no longer used) terms to describe the relative stereochemistry of certain natural products, but finding a definition is proving difficult. While I've been able to make some educated guesses about their meaning, I need to be able to refer to something a little more authoritative than my scribble pad!

If anyone can help me out - even if it's just suggestions for some books or sites that might point me in the right direction - I'd be extremely grateful!

DJF90 - 24-2-2013 at 05:15

Eliel's book/bible on stereochemisty would be my first place to start. If he doesn't have it in there, it doesnt exist.

phlogiston - 24-2-2013 at 05:38

From the IUPAC Compendium of Chemical Terminology, informally known as the Gold Book:
(http://goldbook.iupac.org/A00239.html)
Quote:
Amino acids with two chiral centres were named in the past by allotting a name to the first diastereoisomer to be discovered. The second diastereoisomer, when found or synthesized, was then assigned the same name but with the prefix allo-. This method can be used only with trivial names but not with semisystematic or systematic names. It is now recommended that allo should be used only for alloisoleucine and allothreonine.