0022-326318111946-0824 $01.00/0 stereo-and regiochemistry, but none is generally applicable to all types of substitution patterm2 Recently we reported3 that the reagent system hexachloroacetone (HCA)/triphenylphosphine provides a partial solution to this synthetic problem: primary and secondary allylic alcohols afford nearly quantitative yields of largely or exclusively unrearranged chloride; the geometry of the Py double bond is ...