Study On Silver-Catalyzed Decarboxylative Allylation Of Aliphatic Carboxylic Acids In Aqueous Solution

Radical allylation has been demonstrated to be a versatile method for the construction of C(sp3)-allyl bonds. A variety of allylating agents have been developed for this purpose. Meanwhile, a number of organic compounds can be employed as radical precursors to participate in this type of transformation. However, many radical allylation reactions also suffer from either the use of toxic organotin initiators or the use of excess transition metals or limited substrate scopes. Aliphatic carboxylic acids are promising raw materials for chemical synthesis owing to their high stability, ready availability and low cost. In particular, the Hunsdiecker-type reactions involving the cleavage of C(sp3)-CO2H bonds allow the introduction of various functional groups in a site-specific manner. However, the methods of radical decarboxylative allylation of aliphatic carboxylic acids known by now all require the prior conversion of carboxylic acids into esters, and suffer from the low overall efficiency or limited scope of application. The discovery of general and efficient methods under mild and transition-metal-catalyzed conditions for radical decarboxylative allylation remains a challenging task.In this thesis, we developed a new method for the decarboxylative allylation of aliphatic carboxylic acids. Thus, with AgNO3 as the catalyst and K2S2O8 as the oxidant, the reactions of various aliphatic carboxylic acids with allyl sulfones in aqueous CH3CN solution afforded the corresponding alkenes under mild conditions. A radical mechanism is proposed for this site-specific allylation.In summary, we have successfully developed the one-step decarboxylative allylation of aliphatic carboxylic acids in aqueous solution. This transformation is not only efficient and chemoselective, but also silver-catalytic. In addition, it possesses a broad substrate scope and wide functional group compatibility. In view of its operational simplicity and mild experimental conditions, this method should find important applications in organic synthesis.