The Hydroboration of Propargyl Chloride: A Flexible One-pot Three-component Process Easily Directed Towards the Synthesis of (<i>E</i>)-Homoallylic Alcohols or <i>anti</i>-Homoallylic Alcohols
The hydroboration of propargyl chloride by means of a dialkylborane affords 3-chloro-prop-1-en-1-yl boranes 6 which, in the presence of a quaternary ammonium chloride, rearrange into allylic boranes 9 and 10, precursors of (E)-homoallylic alcohols 7 or anti-homoallylic alcohols 5, respectively. Synthetic protocols for the selective generation of 5 and 7 were developed.
The Hydroboration of Propargyl Bromide. Simple One-Pot Three-Component Routes to (<i>Z</i>)-1-Bromoalk-1-en-4-ols and to <i>a</i><i>nti</i>-Homoallylic Alcohols
toward either the synthesis of (Z)-1-bromoalk-1-en-4-ols 6 or anti-homoallylic alcohols 8. Two one-pot three-component processes were developed based on a sequence of four reactions; preparation of dialkylborane and hydroboration of propargyl bromide are the first steps. Then, quaternization with TEBABr may be carried out either in the presence of the aldehyde when (Z)-1-bromoalk-1-en-4-ols 6 are requested