Concise Process for Pyriftalid Synthesis by Introducing the Mercapto Group Directly from a Nitro Group

A concise and efficient process for the synthesis of pyriftalid is described herein. The improved process features the direct introduction of the mercapto group by one-step substitution of a nitro group using sodium sulfide and elemental sulfur. A systematic study of the key step is also carried out in this article. Compared with previous routes, the optimized route is shorter and avoids a hazardous catalytic reduction and a subsequent diazotization reaction. Salt waste generated in workup is reduced as well. Pyriftalid is obtained in 68% overall yield and 99.88% purity in five steps with 3-nitrophthalic acid as the starting material.

Automated summary

A concise and efficient process for the synthesis of Pyriftalid is described, featuring the direct introduction of the mercapto group in one step. The optimized route is shorter and avoids hazardous reactions and waste generation.