The TMS protected alkyne A can been prepared through a stepwise sequence of Suzuki and Sonogashira...

  

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The TMS protected alkyne A can been prepared through a stepwise sequence of Suzuki and Sonogashira cross-coupling reactions from the precursors B, C, and D. Propose a reaction sequence that selectively yields A as the major product. Provide reagent and conditions for every step. Hint: The optimized sequence requires no more than 3 steps. Me S Me SiMe3 S. Br Br Me3Si A B C D The TMS protected alkyne A can been prepared through a stepwise sequence of Suzuki and Sonogashira cross-coupling reactions from the precursors B, C, and D. Propose a reaction sequence that selectively yields A as the major product. Provide reagent and conditions for every step. Hint: The optimized sequence requires no more than 3 steps. Me S Me SiMe3 S. Br Br Me3Si A B C D