On titanium-promoted hydroborations of alkenes by borohydride and by catecholborane

Article abstract of DOI:10.1021/om00021a038

Some literature reports of catalyzed hydroborations of alkenes by the borohydride anion and by catecholborane were investigated to probe the actual mode of hydroboration. Reactions involving both TiCl₃ and Ti(OⁱPr)₄ seems to involve predominantly formation of BH₃ in situ, although there is some evidence that the metal may be directly involved in a few cases. Ambiguity arises because it is shown that alkyl boronate esters can be formed by exchange between catecholborane and alkylboranes, so formation of these esters is not firm evidence of catalysis.