ORGLIST: Problematic Michael addition

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From: Costa Conn (c.conn$##$uts.EDU.AU)
Date: Tue Jun 29 1999 - 01:28:56 EDT

We have struggled with a poor yielding Michael addition of MVK to a
hindered tert-carbon on a beta ketoester. Conditions tried include PTC,
KOH-MeOH, CsCO3-DMF. Best yields (15%) were obtained with K2CO3 in THF. We
suspect the problem may be steric and maybe due to the fact that it is an
acyclic b-ketoester.

Any suggestions on alternate conditions would be appreciated. We are
contemplating trying a-trimethylsilyl MVK, but it's preparation is a little
involved if it won't work. Anyone have any experience with it. We also want
to avoid Robinson annelation, so we can't push too hard.

Thanks
Costa
Dr Costa Conn
Lecturer, Dept. of Chemistry, Materials & Forensic Science
University of Technology, Sydney
PO Box 123, Broadway, NSW, AUSTRALIA, 2007
Phone: 61-2-9514-1881
Fax: 61-2-9514-1628
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