Pd^II‐Catalyzed Purine‐Directed Ortho Nitration of 6‐Arylpurines by C(sp²)–H Activation: A Practical Approach to Synthesize 6‐(2‐Nitroaryl)‐Purine Derivatives

Abstract

Herein we report a method for PdII‐catalyzed purine‐directed ortho nitration of 6‐arylpurines via C(sp2)–H activation by using tBuONO/O2 as nitration agent. This procedure is highly efficient and produces a range of 6‐(2‐nitroaryl)‐purine derivatives with good chemoselectivity and functional‐group tolerance. The utility of the method is further illustrated in the synthesis of antibacterial agent.

Synthetic Protocols for Aromatic Nitration: A Review

“…Subsequently, NO 2 generated from tert ‐butyl nitrite and react with A‐1 or A‐2 to afford Pd III intermediate, which further oxidized by O 2 to form Pd IV intermediate B‐1 or B‐2. And finally, reductive elimination takes place to give desire nitro product [24] …”

“…And finally, reductive elimination takes place to give desire nitro product. [24] A silver catalyzed regioselective nitration of anilides have developed by Ebrahim Kianmehr and Sepideh Bahrami using K 2 S 2 O 8 as an oxidant and sodium nitrite as a source of nitro in acetonitrile medium (Scheme 17). Here, for the optimization authors employed various amount of catalyst in which 10 mol % of AgNO 2 gives best results in terms of yield.…”

“…Nitration can be carried out by different conditions (Scheme 3). [14,24,33] Here, authors employed various solvents to obtain higher amount of yield in shorter reaction times. So choosing a proper solvent for reaction helps to control thermodynamic and kinetic factors on chemical reaction.…”

Aromatic C–H Methylation and Other Functionalizations via the Rh(III)-Catalyzed Migratory Insertion of Bis(phenylsulfonyl)carbene and Subsequent Transformations

“…Substrates 1a – 1d , 1f – 1k , 1m – 1q , 4a , 4b , 4d , 4e , 4m , 4s , 4u , and 7 were purchased from commercial suppliers without further purification. Substrates 1e , 1l , 2 , 4c , 4f , 4g , 4h , 4i – 4r , ,− and 4t were synthesized according to the reported procedures. Their NMR data and melting points were identical to those reported in the literature.…”