An improved process for the preparation of cis-1,3-diols is described where a
beta hydroxy ketone is treated with a trialkylborane or dialkylalkoxyborane or
a mixture of a trialkylborane and a dialkylalkoxyborane followed by recovery and
reuse of the alkylborane species to convert additional beta hydroxy ketone to the cis-1,3-diol.