REACTIVITY AND SELECTIVITY OF ORTHO-METALATED RHODIUM(II) COMPLEXES IN C-H INSERTION REACTIONS OF ALPHA-DIAZO COMPOUNDS

Regioselective intramolecular C-H insertion reactions of alpha-diazo b eta-keto esters and cc-diazo ketones are mediated by Rh-2[OOCR](4-x)[P C](x), (x = 1, 2; PC = ortho-metalated phosphine; R = CH3, C3F7). In p articular, the intramolecular transformation of 1-diazo-5-methyl-3 -pr opyl-2-hexanone catalyzed by Rh-2[OOCCH3](2)[PC](2) (PC = (C6H4)P(C6H5 )(2), head-to-tail (H-T) configuration) afforded only the tertiary C-H insertion product. By comparison, no C-H insertion reaction was promo ted by doubly metalated complexes with a head-to-head (H-H) configurat ion. Rh-2[OOCR](3)[PC] compounds were found to be less suited for thes e type of reactions.