Subject: StereoEnergetics of Walden inversions

From: "Hr Dr. S. Shapiro" <[email-masked]>
Date: Thu, 20 Oct 1994 17:13:45 +0100 (MET)

Dear Colleagues;

     Can anyone provide me with references about the energetics of Walden in-
versions and the relationship between the "ease" of inversion and the size/
steric parameters of the substitutents attached to the carbon atom at which
the inversion would occur?  Specically, we have been discussing theoretical
possibilities of performing a Walden inversion at sterically-hindered terti-
ary carbon atoms, such as position C-14 of the steroidal skeleton.  Are there
any precedents for an inversion of configuration at the steroidal C-14 posi-
tion (or similarly-hindered natural product tertiary carbon atoms) occurring
via a Walden inversion?  Of course, literature citations would be extremely
welcome.

     Finally, are there any chemical or biochemical precedents for a Walden
inversion occurring in which the departing moiety is a hydride ion or other
hydrogen species?  Again, literature references would be most helpful.

     I thank all responders in advance for generously sharing their informa-
tion with me.

Sincerely,

(Dr.) S. Shapiro
Institut fuer orale Mikrobiologie und allgemeine Immunologie
Zentrum fuer Zahn-, Mund-, und Kieferheilkunde der Universitaet Zuerich
Plattenstrasse 11
Postfach
CH-8028 Zuerich, Switzerland

Internet: [email-masked]
FAX-nr: ( ... + 1) 261'56'83