K_4[Fe(CN)_6]作为氰源在氰基化反应中的应用

Cyanation Reactions with Potassium Hexacyanoferrate(Ⅱ)

过渡金属催化氰基化反应是合成芳基腈化物的重要手段之一。2004年,无毒、廉价的K4[Fe(CN)6]首次被用来代替传统的KCN、NaCN及CuCN等作为氰源用于芳基卤代物的氰基化反应。K4[Fe(CN)6]作为氰源时无需复杂的预处理,其6个氰根均可参与反应。本文主要综述了近年来K4[Fe(CN)6]作为氰源用于卤代芳烃和芳基氟代磺酸酯的氰基化反应,介绍了在钯催化剂和铜催化剂作用下,以K4[Fe(CN)6]为氰源的氰基化反应在配体、反应介质和底物适用范围等方面的研究成果。

Aryl nitriles are important building blocks in modern organic chemistry. They are integral parts of dyes,medicine agrochemicals,as well as many natural products. Many transition metals catalyzed or mediated displacements of aromatic halides by cyanide ions have been developed. The traditional cyanide ion sources are KCN,NaCN,ZnCN,CuCN,（CH3）2C（OH）CN and TMSCN. But these cyanide sources have severe drawbacks： KCN and NaCN are highly poisonous,ZnCN2 and CuCN lead to stoichiometric amounts of heavy metal salt wastes, TMSCN and （CH3）2C（OH）CN are sensitive to moisture. In 2004,Prof. Beller and co-workers described for the first time the use of potassium hexacyanoferrate （ Ⅱ ） （ K4[Fe （ CN）6 ]） as cyanating reagent for the general synthesis of aryl nitriles from aryl bromides. They also found that all the six cyanide ions bound to the iron（ Ⅱ） center were used in the cyanation reaction. Compared with traditional cyanation reagents, potassium hexacyanoferrate （ Ⅱ ） is nontoxic and can be handled without special precautions. Various methods for the synthesis of aryl nitriles with this user-friendly cyanating reagent have been developed. Recently,direct cyanation reactions through transition-metal catalyzed C—H bond activation were reported. This review presents the recent development of Pd and Cu catalyzed cyanation reactions with nontoxic and user-friendly potassium hexacyanoferrate （Ⅱ） as the cyanating reagent.