Formations of mixed β,β-dihaloenals from halogenated secondary alkynols

Iodine and Koser's reagent have been used in stoichiometric amounts to convert 3-bromo-1-phenylpropynol to (Z)-3-bromo-3-iodo-2-phenylpropenal in high yield. The latter is a major component of reaction mixtures of 3-iodo-1-phenylpropynol and bromine with Koser's reagent.