Rhodium-catalyzed synthesis of 1-alkynylphosphine oxides from 1-alkynes and tetraphenylbiphosphine

A rhodium complex RhH(PPh₃)₄ catalyzes the C-P bond forming reaction of 1-alkynes and tetraphenylbiphosphine in the presence of 2,4-dimethylnitrobenzene giving 1-alkynylphosphines and its oxides.     

Direct transformation of organosulfur compounds to organophosphorus compounds: rhodium-catalyzed synthesis of 1-alkynylphosphine sulfides and acylphosphine sulfides

A rhodium-catalyzed method for the synthesis of organophosphorus compounds directly from organosulfur compounds was developed. In the presence of RhH(PPh₃)₄ and depe, the reaction of 1-alkylthioalkynes with tetraethyldiphosphine disulfide gave 1-alkynylphosphine sulfides. The same complex catalyzed the reaction of thioesters giving acylphosphine sulfides.     

Polymerization of arylallenes catalyzed by organo-rhodium(I) and -cobalt (I) complexes to give structurally regulated high-mass polymers

Organorhodium complexes, such as RhH(PPh₃)₄, RhH(CO)(PPh₃)₃, Rh(η³-C₃H₄Ph)(CO)(PPh₃)₂, and RhH(dppe)₂ [dppe = 1,2-bis(diphenylphosphinoethane)], catalyze polymerization of phenylallene and of 4-methylphenylallene at 60 °C. High-molecular-weight polymers (M_n>4×10⁵) are isolated from the reaction products by removing the low-molecular-weight (M_n<3×10³) acetone-soluble fraction. The NMR (¹H and ¹³C{¹H}) spectra of poly(phenylallene) (1) and poly(4-methylphenylallene) (2) show the structure formed through selective 2,3-polymerization of the monomers, while similarly obtained poly(2-naphthylallene) (3) is characterized only by ¹H NMR spectroscopy due to its low solubility in common organic solvents. 4-Fluorophenylallene and 4-(trifluoromethyl)-phenylallene do not polymerize under similar conditions in the presence of RhH(PPh₃)₄ catalyst but are turned into low-molecular-weight oligomers. CoH(N₂)(PPh₃)₃-catalyzed polymerization of phenylallene and 4-methylphenylallene at room temperature gives the corresponding polymers with molecular weights in the range M_n=(9–15)×10⁴, in high yields. © 1997 John Wiley & Sons, Ltd.     

Oxidation/reduction interconversion of thiols and disulfides using hydrogen and oxygen catalyzed by a rhodium complex

RhH(PPh₃)₄ catalyzes reduction of disulfides to thiols by hydrogen and RhH(PPh₃)₄/1,4-bis(diphenylphosphino)butane (dppb) catalyzes oxidation of thiols to disulfides by oxygen.     

Convenient laboratory synthesis of vinylic silicon compounds via the reactions of acetylene with hydrosilanes catalyzed by group-VIII metal phosphine complexes

The hydrosilylation of acetylene (HCCH) with trichlorosilane, triethoxysilane, methyldichlorosilane, methyldiethoxysilane and $\text{n}$-hexyldichlorosilane in an inert solvent in the presence of various phosphine complexes of Group-VIII metals such as Ru, Rh, Pd and Pt, as well as chloroplatinic acid, was investigated. Among the complexes studied, RuCL₂ (PPh₃)₃, PtCl₂ (PPh₃)₂, RhCl (PPh₃)₃, RhH(PPh₃)₄ and Pt(PPh₃)₄ were found to be the catalysts of choice for the selective syntheses of vinyltrichlorosilane, vinyltriethoxysilane, methylvinyldichlorosilane, methylvinyldiethoxysilane and $\text{n}$-hexylvinyldichlorosilane, respectively.     

Rhodium-catalyzed thiophosphinoylation reaction of 1,2-dienes with diphosphine disulfides

In the presence of RhH(PPh₃)₄, the reaction of 1,2-alkadienes, tetramethyldiphosphine disulfide, and camphorsulfonic acid gave (E)-2-dimethylthiophosphinoyl-2-alkenes. The reaction involved the P-P cleavage and the transfer of the thiophosphinoyl group to 1,2-alkadienes with concomitant formation of thiophosphinic anhydride.     

Synthese und reaktivität von siliciumübergangsmetallkomplexen : X. Übergangsmetall → carbanion-übertragung von fluorsilyleinheiten,ein weg zu fluorsilyl-substituierten phosphor-yliden

The trifluorophosphine complex RhH(PF₃)(PPh₃)₃, the analogue of the well-known homogeneous catalyst RhH(CO)(PPh₃)₃, has been synthesised and found to be a highly active catalyst for both the hydrogenation and isomerisation of terminal olefins, and the complex RhH(PF₃)₂ (PPh₃)₂ has been found to bring about rapid isomerisation of terminal olefins.     

Carbon–oxygen bond cleavage in allylic esters promoted by low-valent transition-metal hydride complexes

CoH(N₂)(PPh₃)₃ promotes carbon–oxygen (C? O) bond cleavage in allylic carboxylates to give the corresponding olefins at room temperature. On the other hand, RuH₂(PPh₃)₄ and RhH(PPh₃)₄ are mainly active for C? O bond cleavage at elevated temperature. Reaction proceeds through a mechanism involving predissociation of one of the tertiary phosphines from the RuH₂(PPh₃)₄ and RhH(PPh₃)₄ and competitive coordination of allylic carboxylates and PPh₃ to the vacant site on ruthenium and rhodium. A new six-membered metallocyclic complex, Co(OCOCH₂COCH₃)(PPh₃)₂, has been isolated.     

Effect of the addition of sulfur compounds on the hydroformylation of 1-hexene catalyzed by rhodium systems

The effect of the addition of triphenylphosphine sulfide, thiophene, benzo[b]thiophene and dibenzo[b,d]thiophene on the hydroformylation of 1-hexene catalyzed by rhodium complexes RhH(CO)₄, RhH(CO)₂(PPh₃)₂ and RhH(CO)₂(diphos) was studied. The addition of these sulfur compounds did not affect the activity of non modified rhodium precatalysts, decreased the activity of the PPh₃-modified one and increased the activity of the diphos-modified ones, which is indicative of the sulfur tolerance of these precatalysts. The linear to branched ratio (l/b) varied from 0.5 to 3.4 for the non-modified precatalyst, and from 1.7 to 3.3 for the phosphine-modified ones.     

Rhodium-catalyzed thiophosphinylation and phosphinylation reactions of disulfides and diselenides

Alkyl and aryl dithiophosphinates were synthesized by the reaction of disulfides with biphosphine disulfides in the presence of RhH(PPh₃)₄ and 1,2-diphenylphosphinoethane (dppe). The catalyst also promoted synthesis of thiophosphinates and selenothiophosphinates from disulfides and diselenides.     

Metal catalysed Brooke rearrangement of 3-Halo-1-(trimethylsilyl) propan-2-one (Halo = Cl or Br)

The complexes [IrH(CO)(PPh₃)₃], trans-[IrCI(CO)- (PPh₃)₂], [RhH(PPh₃)₄], [Pd(PPh₃)₄], [Pt(trans-stilbene)(PPh₃)₂] and [Pt(η³-CH₂-COCH₂)-(PPh₃)₂] catalyse the rearrangement of Me₃SiCH₂C(O)CH₂Cl to CH₂?C(OSiMe₃)-CH₂Cl.     

Reactivity of olefin an acetylene complexes of platinum(0) towards tetrachloro-o-benzoquinone

Tetracloro-o-benzoquinone reacts with (diphenylacetylene)bis(tirphenylphosphine)platinum(0) to give the novel platinum(II) diphenylacetylene complex, Pt(C₆Cl₄O₂)PhCCPh)(PPh₃), (I), which reacts with hydrogen halides to give the compelexes cis-PtX₂(PhCCPh((PPh₃), (X = Cl or Br). Hydrogen chloride also readily removes the tetrachloro-o-benzoquinoneligand from the adducts Ni(C₆Cl₄O₂)(Ph₂PCH₂CH₂PPh₂) and M(C₆Cl₄O₂)(PPh₃)₂, (M = Pd or Pt) but it has no reaction upon Ir(Cl)(C₆Cl₄O₂)(CO)(PPh₃)₂ at room temperature. The acetylene in (1) is susceptible to nucleophilic attact and reaction with diethylamine gives the vinyl adduct Pt(C₆Cl₄O₂)(CPhCPh)NHEt₂)(PPh₃). Other reactions of (I) have also been studied. Attemps to prepare other olefin or acetylene complexes of platinum(II) by the action of tetrachlor-o-benzoquinone on the complexes Pt(L)(PPh₃)₂, (L = PhCCH,(Et)(Me)(HO)CCCC(OH)(Me)(Et), HOCH₂OH, CF₃CCCF₃, CF₂CF₂, CF₂CH₂ or trans-PhCHCHPh) are also described.     

Rhodium-catalyzed sulfur atom exchange reaction between organic polysulfides and sulfur

RhH(PPh₃)₄ and cis-1,2-bis(diphenylphosphino)ethylene (dppv) catalyze the exchange of sulfur atoms between sulfur and organic polysulfides. The exchange of dialkyl trisulfides with sulfur proceeds at a high efficiency within 5 min at room temperature yielding a mixture of organic polysulfides.     

Rhodium-catalyzed arylthiolation reaction of nitroalkanes, diethyl malonate, and 1,2-diphenylethanone with diaryl disulfides: control of disfavored equilibrium reaction

In the presence of catalytic amounts of RhH(PPh₃)₄ and 1,2-bis(diphenylphosphino)ethane (dppe), 1-nitroalkanes reacted with a diaryl disulfide giving 1-arylthio-1-nitroalkanes in air. The equilibrium to form thermodynamically disfavored products was shifted by the rhodium-catalyzed oxidation of thiols to disulfides and water. The thiolation reaction of cyclic nitroalkanes proceeded in high yields provided that suitable diaryl disulfides were employed depending on the substrate: di(p-chlorophenyl) disulfide was used for the thiolation reaction of 1-nitroalkanes, 1-nitrocyclopentane and 1-nitrocycloheptane with acidic α-protons (pK_a 16 and 17); di(p-methoxyphenyl) disulfide for 1-nitrocyclobutane and 1-nitrocyclohexane with less acidic α-protons (pK_a ca. 18). Related reactivities were observed in the thiolation reactions of malonate and 1,2-diphenylethanone.     

Synthesis and reactivity of rhodium fluoro complexes

[RhH(CO)(PPh₃)₂] (1) reacts with Et₃N·3HF to give the fluoro compound [RhF(CO)(PPh₃)₂] (2). In a comparable reaction [RhF(PEt₃)₃] (5) has been obtained from [RhH(PEt₃)₃] (3) or [RhH(PEt₃)₄] (4) with substoichiometric amounts of Et₃N·3HF in THF. If the latter reaction is carried out in benzene, the complexes 5, cis-mer-[Rh(H)₂F(PEt₃)₃] (6) and cis-fac-[Rh(H)₂F(PEt₃)₃] (7) are obtained. Treatment of 5 with HCl in ether effects the generation of [RhCl(PEt₃)₃] (8) and the bifluoride compound [Rh(FHF)(PEt₃)₃] (9), which can be converted into 5 in the presence of Et₃N and Cs₂CO₃. Treatment of 5 with HSiR₂Ph (R=Ph, Me) leads to the formation of 3 and the rhodium(III) silyl complexes fac-[Rh(H)₂(SiR₂Ph)(PEt₃)₃] (10: R=Ph, 11: R=Me).     

Rhodium-catalyzed α-methylthiolation reaction of unactivated ketones using 1,2-diphenyl-2-methylthio-1-ethanone for the methylthio transfer reagent

In the presence of catalytic amounts of RhH(PPh₃)₄, 1,2-bis(diphenylphosphino)ethane (dppe), and dimethyl disulfide, ketones without α-activating groups were α-methylthiolated with 1,2-diphenyl-2-methylthio-1-ethanone giving α-methylthio ketones. The reaction of unsymmetrical ketones proceeded at the more substituted carbons. The initial formation of kinetic α-methylthiolated products followed by their rearrangement to thermodynamic products was observed in the reaction of α-phenyl ketones. Aldehydes, phenylacetate, and phenylacetonitrile were also α-methylthiolated under these conditions.     

Rhodium-catalyzed interconversion between acid fluorides and thioesters controlled using heteroatom acceptors

A rhodium complex catalyzed the equilibrium acyl transfer reaction between acid fluorides and thioesters. In the presence of fluoride or thiolate acceptors, the reaction could be shifted to either product. RhH(PPh₃)₄-dppe catalyzed the reaction of acid fluorides and diorgano disulfides in the presence of triphenylphosphine giving thioesters, which was accompanied by triphenylphosphine difluoride. The same complex catalyzed the reaction of aryl thioesters and hexafluorobenzene giving acid fluorides, which was accompanied by 1,4-di(arylthio)-2,3,5,6-tetrafluorobenzenes.     

Two types of rhodium-catalyzed CS/CS metathesis reactions: formation of CS/CS bonds and CC/SS bonds

A rhodium complex catalyzes two types of single bond metathesis reactions of two CS bonds depending on the added ligand: CS/CS to CS/CS metathesis and CS/CS to CC/SS metathesis. In the presence of a catalytic amount of RhH(PPh₃)₄ and 1,1′-bis(diphenylphosphino)ferrocene (dppf), two 1-alkylthioalkynes exchange alkylthio groups to give equilibrium mixtures of four 1-alkylthioalkynes. When tris(p-methoxyphenyl)phosphine or diphenylmethylphosphine is used, 1,3-butadiynes are obtained.     

Rhodium(I) catalyzed decomposition of formic acid

Rh(C₆H₄PPh₂)(PPh₃)₂ catalyzes the decomposition of formic acid to CO₂ and H₂. The initial step is the oxidative addition of formic acid to produce the intermediate Rh(HCO₂)(PPh₃)₃, which probably is followed by β-hydride elimination, to produce CO₂ and RhH(PPh₃)₃. The latter reacts with formic acid to produce H₂ and to reform Rh(HCO₂)(PPh₃)₃.     

An activated catalyst RhH(PPh3)4‐dppe‐ Me2S2 for α‐methylthiolaton of α‐phenyl ketones

In the presence of catalytic amounts of RhH(PPh₃)₄, 1,2‐bis(diphenylphosphino)ethane (dppe), and dimethyl disulfide, cyclic and acyclic α‐phenyl ketones reacted with p‐cyano‐α‐methylthioa‐ cetophenone giving α‐methylthio‐α‐phenylketones. The activated catalyst containing dimethyl disulfide was effective for the α‐methylthiolation reaction of these less reactive substrates. © 2010 Wiley Periodicals, Inc. Heteroatom Chem 22:18–23, 2011; View this article online at wileyonlinelibrary.com . DOI 10.1002/hc.20650