3-Chloro-2-aza-2-propeniminium Units as Versatile Building Blocks in Organic Synthesis

3-Chloro-2-aza-2-propeniminium salts, 3-chloro-2-aza-2,4-pentadieniminium salts, and 3-chloro-2,4-diaza-2,4-pentadieniminium salts are reviewed as useful building blocks for N-containing open-chain and especially heterocyclic products. These readily available educts represent hetero analogues of imides possessing high reactivity and hence allowing a variety of new syntheses. 1. Introduction 2. Preparation of 3-Chloro-2-aza-2-propeniminium Compounds 3. Properties of 3-Chloro-2-aza-2-propeniminium Compounds 4. Synthetic Application of 3-Chloro-2-aza-2-propeniminium Salts and Related Compounds 4.1. General Reaction Behavior 4.2. Synthesis of Open-Chain Compounds by Reactions with Nucleophiles 4.3. Synthesis of Open-Chain Compounds by Reactions with Electrophiles 4.4. Synthesis of Heterocyclic Compounds