From: Jonathan Brecher (jsb2$##$camsoft.com)
Date: Mon Mar 01 1999 - 09:50:06 EST
> I'm having a heck of a time naming this structure, and numbering the =
>ring system for that matter. If anyone can help, THANKS!!
>
>http://www.siue.edu/~dbaker/unknown.htm
There are several ways to answer this question.
a) According to which set of recommendations do you want to name it? CAS
and IUPAC recommend different names. Different editions of their naming
systems also recommend different names. The name you get depends on which
naming system you use.
b) Do you want *a* name or *the* name? As above, you can only get *the*
name in the context of a specific edition of a specific naming system. On
the other hand, if you just want *a* name, then anything unambigous might
do.
c) What level of adherance do you want? Both the CAS and the IUPAC naming
systems are arcane to say the least. It's much easier to get a "CAS-like"
or "IUPAC-like" name than to get *the* recommended CAS or IUPAC name, even
for a specific edition of the naming sytem.
Those said, for a simple structure such as the one you show, the easiest
solution is probably just to defer to software packages that claim to do
the job. There are two commercial packages that implement large portions
of the IUPAC and/or CAS recommendations, but neither is (or claims to be)
complete. ACD/Name is available from ACDLabs
(http://www.acdlabs.com/products/name/); Autonom is available from
Beilstein (http://www.beilstein.com/products/autonom/) and is also included
as part of ChemDraw Ultra 5.0
(http://www.camsoft.com/products/ProdInfo.cfm?pid=169). According to
Autonom, your structure would be named:
2-Chloro-5-hydroxymethyl-4-oxa-tricyclo[5.2.1.0(2,6)]dec-8-en-3-one, where
the (2,6) part is superscripted and not in parentheses. To this you could
add stereochemistry indicators if you are interested in this particular
conformation: (1R, 2R, 6S, 7R)-
An alternative, focusing on the main two-ring structure:
(3abeta, 4beta, 7beta,
7abeta)-7a-chloro-3-hydroxymethyl-4,7-methano-3a,4,7,7a-tetrahydro-isobenzofuran
-1(3H)-one
Yet a third alternative, focusing on the chemistry:
endo-Diels-Alder adduct of cyclopentadiene and
3-chloro-5-hydroxymethyl-furan-2(5H)-one.
Any of these should be clear an unambiguous to a practicing chemist. Which
you choose is more a matter of what sort of thing you want to highlight.
Jonathan Brecher
CambridgeSoft Corporation
jsb2$##$camsoft.com
__________________
ORGLIST - Organic Chemistry Mailing List
WWW Homepage and Archive: http://www.orglist.net/
List coordinator: Joao Aires de Sousa (jas$##$mail.fct.unl.pt)
This archive was generated by hypermail 2.1.4 : Fri Sep 19 2003 - 12:15:04 EDT