Synthesis of Iminium Salts

The synthesis of iminium salt 85 by soda-lime pyrolysis through an intermediate enamine (83CJC2016) is inferior to that of salt 60 (Scheme 16). Cathodic cyclization of l-(E-oxoalkyl)pyridinium salts gives dia-stereomeric hydroxy compounds 86 and 87 in yields of 14-16% each (95AGE2007). 

Synthesis of Iminium Salts, Orthoesters and Related Compounds. Kantleh-ner, W, In Comprehensive Organic Synthesis Trost, B. M., Fleming, I., Eds. Pergamon Press Oxford, 1991 Vol. 6, p 485. 

Synthesis of Iminium Salts, Orthoesters and Related Compounds... 

In analogy to the synthesis of iminium salts (Section 4.2.2.1.), acyiiminium ions (60) can be obtained from carbonyl precursors (1), such as ketones or aldehydes, and carboxylic acid amides (62 Scheme 30). In addition, other amides can be used, such as p-toluenesulfonamides, which lead to the corresponding N-tosylated iminium salts. ... 

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