Hydrido−Rhodium(I) and −Iridium(I) Complex Promoted Ring-Opening Isomerization of Unsymmetrically Substituted Methylenecyclopropanes into 1,3-Dienes. Structures of Intermediates and Reaction Pathways

Abstract

Phenyl-1-methylenecyclopropane and 2,2diphenyl-1-methylenecyclopropane react with MH(CO)-(PPh 3 ) 3 (M ) Rh, Ir) to produce 1,3-dienes or the intermediate Rh and Ir complexes having a 3-butenyl ligand, depending on the conditions. The structures and chemical properties of the obtained complexes suggest plausible pathways for the ring-opening isomerization of the methylenecyclopropanes to the corresponding dienes.

Reactivity and mechanism in the ring-opening of cyclopropylmethylplatinum(IV) complexes

“…The isomeric 3-butenyl complex 13 is more stable but it cannot be formed directly from 11. This explains in a qualitative way why the ring opening is more difficult in the octahedral organoplatinum(IV) complex 2 than in square planar complexes which are more commonly used in catalysis [1,2,[7][8][9][10][11][12][13][14][15][16][17][18][19].…”

“…The transition metal may play a direct role in the ring-opening step, but it is also well known that cyclopropylmethyl to butenyl isomerisation may occur within the organic free radicals, cations or anions [3][4][5][6]. Some insights into the mechanisms have been gained by study of stoichiometric reactions, but there are still surprisingly few known examples of thermally stable transition metal complexes with cyclopropylmethyl or cyclobutylmethyl ligands to act as model compounds [7][8][9][10][11][12][13][14][15][16][17][18][19][20]. Cyclopropylmethyl complexes are often generated by insertion of methylenecyclopropane [1,2,[7][8][9][10][11][12][13] while cyclobutylmethyl complexes have usually been prepared by transmetalation [16][17][18].…”

Selectivity in Metal‐Catalyzed CarbonCarbon Bond Cleavage of Alkylidenecyclopropanes

“…(22) was isolated and fully characterized through a selective proximal carbonÀcarbon bond cleavage. [15] Use of [D 15 3 ] results in selective deuteration at the gposition of the ligand. The carbon À carbon activation involves the initial insertion of the C=C double bond into the RhÀH bond and an ensuing balkyl elimination [16] of the resulting cyclopropylmethyl rhodium complex (Scheme 5).…”

Alkenyl complexes of platinum group metals: a platform for diverse reactivity patterns

“…Orthometalation of the produced 3‐butenyl rhodium complex leads to 56 . The hydrocarbon ligand of the initially formed Rh complex has no β‐hydrogen and causes orthometalation to give the final product upon heating at relatively high temperature (Scheme ).…”