ISSN:
0570-0833
Keywords:
Pyrylium salts
;
Pyridinium salts
;
Synthetic methods
;
Amines
;
Chemistry
;
General Chemistry
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
Notes:
The first pyrylium salt was isolated some 80 years ago, yet up to the 1950s only moderate interest was taken in the preparation, properties and uses of such salts. However, the past thirty years has seen a phenomenal growth in the literature pertinent to this area of chemistry: the importance of pyrylium salts as intermediates has been realized. They are readily prepared by a variety of generally applicable routes, and they are highly reactive towards nucleophiles. Together, this enables the convenient synthesis of a great variety of acyclic and heterocyclic compounds. We have used highly substituted pyrylium salts for the two-step conversion of the amino group in alkylamines RNH2 into numerous other functionalities. In the first step, the pyrylium salts are converted with the amines into N-substituted pyridinium salts, which, in the second step, react with Nu⊖ to give the desired products RNu. In some cases the R moiety is also changed, e.g. by elimination. Studies of the reactions of these pyridinium salts have allowed interesting insights into the mechanisms of nucleophilic substitution, in addition to rendering aliphatic amines important synthetic intermediates. Thus, the method complements the diazotization procedure for the transformation of arylamines.
Additional Material:
1 Tab.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/anie.198404201
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