Alkoxy‐substituted <i>N</i>‐acyliminium salts — synthesis, structure, reactivity

Abstract

Abstract Alkylation of aliphatic imides 5 by use of oxonium salts takes place at one of the carbonyl oxygen atoms, leading to alkoxy‐substituted N ‐acyliminium salts 1 . These new reactive intermediates are fully characterized by IR, 1 H‐ and 13 C‐NMR spectroscopy and X‐ray analysis. The stereochemical and dynamical properties of the model compounds 6, 7 are investigated by ab initio model calculations (MP2/6–31G * //6–31G * ). The barrier of rotation around the central C—N bond in 6 is calculated to 10.2 kcal/mol. The reaction with CH acids 8 yields new types of enamides ( 9 ); primary amines 10 are converted to N ‐acylamidines 11 . Primary amidines 12 react with 1 to form new 1,3‐diazabutadiene derivatives 13 . The reaction with primary amides 14 gives N,N ‐bisacylamidines 15 . With primary N ‐acylamidines 16 new doubly azavinylogous imides 17 (1‐oxa‐3,5‐diazahexatriene derivatives) are formed.