Synthesis, Structure, and Catalytic Activity of Some New Chiral 2-Menthylindenyl and 2-Menthyl-4,7-dimethylindenyl Rhodium Complexes

Abstract

Optically active rhodium complexes containing the chiral, menthyl‐substituted indenyl ligands (−)‐2‐menthyl‐4,7‐dimethylindene and (−)‐2‐menthylindene are described. Metathesis reactions of the chiral lithium salts of these indenyl systems with the appropriate starting materials yielded the complexes (−)‐(2‐menthyl‐4,7‐dimethylindenyl)Rh(CO)2 (2), (−)‐(2‐menthyl‐4,7‐dimethylindenyl)Rh(dppe) (3), (+)‐(2‐men‐ thylindenyl)Rh(dppe) (5), (−)‐(2‐menthylindenyl)Rh(PMe3)2 (6), and (−)‐(2‐menthylindenyl)Rh(nbd) (8). All compounds obtained were diastereomerically pure. The structures of 2, 3, and 6 were determined by single crystal X‐ray diffractome‐ try. Complexes 3 as well as (−)‐bis(η2‐ethylene)(η5‐2‐menthyl‐4,7‐dimethylindenyl)rhodium(I) (9), (−)‐(cycloocta‐1,5‐diene)(η5‐1‐menthyl‐4,7‐dimethylindenyl)rhodium(I) (10), (−)‐(cycloocta‐1,5‐diene)(η5‐2‐menthyl‐4,7‐dimethylindenyl)rhodium(I) (11), and (−)‐(cycloocta‐1,5‐diene)(η5‐2‐menthylindenyl)rhodium(I) (12) were found to be active as double bond hydrogenation catalysts. Two of them proved to induce asymmetry up to 18% ee. These complexes also promote the hydroformylation of olefins yielding both linear and branched aldehydes in varying ratios but hardly transfer chirality.

103Rh NMR Chemical Shifts in Organometallic Complexes: A Combined Experimental and Density Functional Study

“…A search of rhodium indenyl complexes gave 79 structures, for which the slip distortion parameter can vary by about 0.08 Å. For example, Δ is 0.200(7) Å in dicarbonyl( η 5 ‐indenyl)rhodium (VATYUK),23 0.205(5) in dicarbonyl( η 5 ‐4,5,6,7‐tetramethylindenyl)rhodium (KUWPOH),23 but decreases to 0.186 Å in (−)‐dicarbonyl( η 5 ‐2‐menthyl‐4,7‐dimethylindenyl)rhodium (MIFFIQ) 41. The Δ value is 0.161 Å in bis( η 2 ‐ethylene)( η 5 ‐indenyl)rhodium,42 0.168 Å in (−)‐bis( η 2 ‐ethylene)( η 5 ‐2‐menthyl‐4,7‐dimethylindenyl)rhodium (MORCOL)43 and 0.118 Å in [ μ 2 ‐2‐( η 5 ‐cyclopentadienyl)‐2‐( η 5 ‐indenyl)propane]bis[bis( η 2 ‐ethylene)]dirhodium (POZTIH) 44.…”

A chiral menthyl cyclopentadienyl molybdenum tricarbonyl chloro complex: Synthesis, heterogenization on MCM-41/MCM-48 and application in olefin epoxidation catalysis

“…A menthyl moiety attached to the cyclopentadienyl ring of metallocenes is a powerful tool for the amplification of chiral information [36][37][38][39][40][41][42][43][44][45]. Chiral menthyl-derived cyclopentadienyl and indenyl complexes of various transition metals are being widely exploited in different stoichiometric and catalytic asymmetric reactions and with respect to asymmetric structural effects [36][37][38][39][40][41][42][43][44][45].…”

“…Chiral menthyl-derived cyclopentadienyl and indenyl complexes of various transition metals are being widely exploited in different stoichiometric and catalytic asymmetric reactions and with respect to asymmetric structural effects [36][37][38][39][40][41][42][43][44][45]. In the case of molybdenum, the complexes (À)-[(2-menthylindenyl)Mo(CO) 3 I], allyl(2-menthylindenyl)-Mo(CO) 2 and (À)-[(2-menthylindenyl)Mo(CO) 3 ]Li(THF) have been synthesized [38,39].…”

Indenylmetal Catalysis in Organic Synthesis

“…[81] Though both complex 125 and planar chiral 126 exhibited excellent reactivity, chiral succinic acid 128 was isolated in low ee . These two complexes can also be used for branched-selective hydroformylation of styrene to 2-phenylpropanal, but no enantioselectivity was observed.…”