A mild and extra activator-free dehydrative alkylation of stabilized phosphonium ylides with allylic alcohols in water is developed in the presence of [Pd(allyl)Cl] 2 /dppf catalyst. A wide range of aryl, heteroaryl, alkyl and even allylic tertiary alcohols can readily react with stabilized phosphonium ylides with high regioselectivity for the efficient synthesis of functionalized skipped dienes in moderate to high yields. The role of water was investigated by means of a high-resolution mass spectrum and diffusion-ordered spectroscopy nuclear magnetic resonance, and the results revealed that water might play a crucial role in the formation of the p-allylpalladium complex via hydrogen bond. However, the present method is not suitable for water-sensitive phosphonium ylides.

A mild and regioselective bromination of phenols with the cheap and easily-available HBr is developed. By replacing the common used dimethyl sulfoxide (DMSO) with sulfoxides bearing sterically hindered substituents, the desired brominated phenols could be obtained in moderate to high yields with up to 99/1 regioselectivity. This method could be easily scaled up to 50 mmol scale and has the potential to isolate the desired product by simple extraction and recrystallization, showing great practicality of this new method.