Rhodium-carbenoid mediated O-H insertion reactions. O-H insertion vs. H-abstraction and effect of catalyst

Article abstract of DOI:10.1016/S0040-4020(01)81117-0

The synthesis and rhodium mediated O-H insertion reactions of a wide range of diazo compounds are described. The rate at which the diazo compounds decompose in the presence of 2-propanol and the rhodium catalyst is strongly dependent on the electron withdrawing group(s) attached to the diazo carbon, with diazophosphonates being the least reactive. Insertion into the O-H bond of methanol, t-butanol and phenols was also investigated, as well as the effect of catalyst. In some cases 'reduction' of the diazo group to the corresponding CH₂ group competes with O-H insertion, although this is highly catalyst and substrate dependent. Of the catalysts used, rhodium(II) trifluoroacetamide is the most effective for O-H insertion reactions.