In Situ Generation of Unstable Difluoromethylphosphonate-Containing Diazoalkanes and Their Use in [3+2] Cycloaddition Reactions with Vinyl Sulfones

A [3 + 2] cycloaddition reaction of unstable difluoromethylphosphonate-containing diazoalkanes with vinyl sulfones under simple reaction conditions is developed, which provides an efficient route toward functionalized fluorinated pyrazolines derivatives in good chemical yields. The difluoro diazoalkanes are generated in situ using t-BuONO for the diazotization of (beta-amino-alpha,alpha-difluoroethyl)phosphonates, and their stabilities and reactivities were carefully investigated.

Automated summary

An efficient route for the synthesis of functionalized fluorinated pyrazolines derivatives was developed by conducting a [3+2] cycloaddition reaction of unstable difluoromethylphosphonate-containing diazoalkanes with vinyl sulfones under simple reaction conditions. The difluoro diazalkanes were generated in situ using t-BuONO for the diazotization of (beta-amino-alpha,alpha-difluoroethyl)phosphonates, demonstrating good stability and reactivity.