Recent Synthetic Methods in Diazo Chemistry

This review is concerned with the application of recently developed methods for the synthesis of aliphatic diazo compounds. Transformations of diazo compounds involving retention of the diazo group (substitution, addition, cleavage), and the variations of diazo-group transfer reactions in which azides act as donor for the diazo group are described. 1. Transformation of Diazo Compounds with Retention of the Diazo Function 1.1 Substitution Reactions 1.1.1. Nitration 1.1.2. Halogenation 1.1.3. Acylation 1.1.4. Metallation 1.1.5. Substitution Reactions via Metal Derivatives 1.2. Addition Reactions 1.2.1. Additions to Carbonyl Compounds 1.2.2. Additions to Electron-Rich Olefins 1.3. Cleavage Reactions 2. Syntheses of Diazo Compounds by Diazo-Group Transfer 2.1. to Active Methylene Compounds Using Tosyl Azide 2.1.1. Diazocyclopentadienes and Diazocyclohexadienes 2.1.2. α-Diazocarbonyl Compounds 2.1.3. α-Diazosulfonyl Compounds 2.1.4. α-Diazophosphono- and α-Diazophosphinyl Compounds 2.2. to Methylene Compounds Using Azidinium Salts 2.3. to Formyl Compounds 2.4. to Activated Olefins 2.5. to Alkynes