文档介绍:Tctmhcdron Letters. Vol. 33. No. 15. pp. 2005-2008,1992 $ + .oo
Printed in Great Britain Pergamon Press Ltd
A New Route to Trans 2,SDialkylpyrrolidines
Francoise DUMAS and Jean d’ANGEL0
Laboratoire de anique, Faculte de Pharmacie
5, rue Jean-Baptiste Clbment, 92290 Ch?uenay-Malabry (France)
Key-words : Intramolecular Michael-type N-heterocyclization, trans 2J-dialkylpyrrolidines, ant venoms.
Abstract : Benzylic amines 8 react with ketoenoates 7 yielding, after reduction of the primary adducts, 2,5-
dialkylpyrrolidines 9 (trans isomer predominating). This reaction has been applied to the synthesis of trans 2-
of
heptyl-5-ethylpyrrolidine, ponent of the venom fire ant (Solenopsis punctaticeps).
We recently disclosed that ketoenoates 1, 4a and 4b, in which the keto group is separated from the
enoate moiety by a 3,4 or 5 carbon-atom chain, are cyclized in the presence of (R)- 1-phenylethylamine, leading
to cyclanones 3,6a and 6b respectively with a moderate to excellent stereoselectivityl. Conversions (1 + 3,
4a + 6a and 4b + 6b) involve in fact the corresponding intermediate chiral imines (2,5a and 5 b
respectively, which have been isolated and characterized) which underwent a subsequent intramolecular Michael
carbocyclization.
-0 *‘f/
I
COOMe COOMe COOMe
1
2 3
-
4a: n=l 5 6
4b: n=2
In this