Synthesis of 2-phenoxybutanal from but-1-yne
Water, BH3, H2O2, NaOH


This reaction, an hydroboration, yelds butanal


Br2, H2SO4


This reaction, carried without light, is an alpha carbon bromination, and yelds 2-bromobutanal


Sodium phenoxide


This is a simple Williamson Ether Synthesis, which yelds the final product