Premium
Reaction of the 5‐Azoniafulvene Ion with Enamines: A New Approach to Pyrrolizines
Author(s) -
Schärer Daniel,
Jindra Vladimir,
Bringhen Alain O.,
Burger Ulrich
Publication year - 1991
Publication title -
helvetica chimica acta
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.74
H-Index - 82
eISSN - 1522-2675
pISSN - 0018-019X
DOI - 10.1002/hlca.19910740824
Subject(s) - chemistry , yield (engineering) , salt (chemistry) , pyrrole , chloride , ion , medicinal chemistry , enamine , mannich reaction , organic chemistry , catalysis , materials science , metallurgy
Abstract The synthesis of N , N ‐dimethyl‐ N ‐[(pyrro‐1‐yl)methyl]anilinium chloride ( 14 ) and of the corresponding p ‐toluidinium salt 15 is described. These salts, when dissolved in polar solvents, are shown to be in equilibrium with 1‐(chloromethyl)pyrrole ( 17 ) and thereby potentially with the 5‐azoniafulvene ion ( 2 ). Consequently, they react under very mild conditions (MeCN, 60°) with enamines to give pyrrolizine derivatives in acceptable yield (40–50°). The process is rationalized in terms of an initial Mannich ‐type reaction which is immediately followed by acyclization.