Rhodium complex derivative

Subsequently, it was shown that rhodium complexes derived from diphosphi-nites, diphosphonites, and diphosphites - as well as hybrid ligands - are similarly active and selective to diphosphines [46 i],... 

The hydrogenation of ketones with O or N functions in the a- or / -position is accomplished by several rhodium compounds [46 a, b, e, g, i, j, m, 56], Many of these examples have been applied in the synthesis of biologically active chiral products [59]. One of the first examples was the asymmetric synthesis of pantothenic acid, a member of the B complex vitamins and an important constituent of coenzyme A. Ojima et al. first described this synthesis in 1978, the most significant step being the enantioselective reduction of a cyclic a-keto ester, dihydro-4,4-dimethyl-2,3-furandione, to D-(-)-pantoyl lactone. A rhodium complex derived from [RhCl(COD)]2 and the chiral pyrrolidino diphosphine, (2S,4S)-N-tert-butoxy-carbonyl-4-diphenylphosphino-2-diphenylphosphinomethyl-pyrrolidine ((S, S) -... 

COBALT AND RHODIUM COMPLEXES DERIVED FROM OFCOT AND PERFLUOROBICYCLO[4.2.0]OCTA-2,4,7-TRIENE... 

E. Pentamethylcyclopentadienyl Cobalt and Rhodium Complexes Derived from OFCOT... 

An N-heterocyclic carbene rhodium complex derived from L-proline has been reported (Scheme 10). The rhodium complex 9 is active catalyst for the addition reaction of arylboronic acids to aldehydes, albeit with low ee s (21% at best) [29]. 

The Shi and Crabtree groups have found that iridium and rhodium complexes derived from BINAM (l,T-binaphthyl-2,2 -diamine) are also capable of the transformation. While Shi s Rh catalyst 37 [81] gave similar results to those reported by Gade, Crabtree s Ir catalyst 38 [82] was less effective, providing optical induction of only 60%. 

P solid-state NMR spectra were used to characterise Si02-tethered rhodium complexes derived from RhCl(PPh3)3 or RhH(CO)(PPh3)3.210... 

In 2005, Sames and co-workers reported the highly selective (>50 1) C2-arylation of NH-free indoles using a rhodium complex derived from an electron-deficient phosphine as the catalyst, CsOPiv as a base, and iodoar-enes as coupling partners (Scheme 37, 05JA4996). Mechanistic studies revealed that a highly electrophilic Ar-Rh(III) complex was formed in situ through the oxidative addition of aryl iodide to Rh(I) (Scheme 38). Then the displacement of the phosphine ligand by indoles takes place, followed by... 

Notably, an independently synthesized air-stable rhodium complex derived from preligand 24 was shown to be catalytically competent furthermore, spectroscopic data indicated the formahon of complex 28. Therefore, a mechanism was proposed that proceeded via an in situ generation of the corresponding phosphinite, with subsequent cyclometallation. 

There are rather few water-soluble hydrogenation catalysts. A number of rhodium complexes derived from ligands such as (PH2PCH2CH2)2NC0C6H4S03" are active in this way. " Catalysts have been developed for hydrogenation of ketonescarboxylic acids/ esters/ nitriles/ and nitro compounds. 

Si02-tethered rhodium complexes, derived from Rh(CO)2(acac) and 3-(mercapto) propyl- and 3-(l-thioureido)propyl-functionalized silica gel, were used as catalysts in the hydroformylation of various vinyl arenes and vinyl acetate. Conversions, che-moselectivity, and regioselectivity obtained with the Si02-tethered catalysts were comparable with those of the well-known homogeneous rhodium catalysts [85]. 

Rhodium complexes derived from chelating bisphosphines anchored to an asymmetric, ancillary Cp-Re complex exhibit moderate enantioselectivity in the hydrosiiation of phenyl/alkyl ketones with Ph2SiH2. A tra i-chelating, planar-chiral bisphosphine 40, based on a biferrocenyl motif, forms Rh complexes that are... 

Cri.i iN. W. R.. and Y. SuGi Asymmetric Hydrogenation Catalyzed by Diphos-phinite Rhodium Complexes Derived From A Sugar. Tetrahedron Letters 1978, 1635. 

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