Modified Click-Style Sonogashira Coupling Reactions Involving Silyl-Protected Alkynes

Barbour, Kimberly, Rachel Beltman, Yousif Brikho, Nicholas Boynton, Nadine Husseini, Mary Payne, Bennett Ross, Kevin Suiter, and Matthew Mio

A modified click-style Sonogashira coupling reaction has been developed which can couple aryl bromides to silyl-protected alkynes at elevated temperature. Excellent yields are possible, the transformation is tolerant of electron-deficient and –rich aryl halide systems, and minimum homocoupling products are observed. The transformation protocol involves Pd(dba)2 catalyst, sodium ascorbate, copper (II) sulfate, and either 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) or trimethylamine as the base. The solvent system makes use of an acetonitrile/water mixture and it is likely the combination of the water and Cu2+ which allows for in situ silyl protecting group removal and subsequent Sonogashira coupling.