Tetrakis methyl

Tetrakis [methyl ene(3,5-di-tert-butyl-4-hydroxyhydrocinnamate)]methane [6683-19-8]... [Pg.976]

The reaction of 1,2,4,5-tetrafluorobenzene in NVV -dimethylimidazolidin-l-one (DMT) with sodium or alkaline methyl mercaptide gives l,2,4,5-tetrakis(methyl-thio)benzene [26] (equadon 16). [Pg.505]

R,5S)-(-)-6,6-Dimethyl-3-oxabicyclo[3.1,0]hexan-2-one. Highly tnantioselective Intramolecular Cyclopropanation Catalyzed by Dirhodium(ll) Tetrakis[methyl 2-pyrrolidone-5(R)-carboxylate],... [Pg.290]

Experimental Procedure 4.1.1. Preparation of an Enantiomerically Pure Rho-dium(II) Gomplex Dirhodium(II) Tetrakis[methyl 2-oxo-l-(3-phenylpr( anoyl)-4(S)-imidazolidinecarboxylate] Rh2(4S-MPPIM)4(MeCN)2 [1000]... [Pg.175]

Desymmetrization strategy in enantioselective oxonium ylide formation/[l,2]-shift reaction has been reported by Doyle and co-workers.With dirhodium(ii) tetrakis[methyl l-(3-phenylpropanoyl)-2-oxoimidazolidine-4(3 )-carboxylate] [Rh2(43 -MPPIM)4] as the catalyst, up to 88% ee is obtained (Equation (7)). [Pg.158]

The preparation of tetrakis(trifluorophosphine)nickel-(0), tetrakis (methyl-difluorophosphine) nickel- (0), and tetrakis (phenyldifluorophosphine) nickel- (0) from the corresponding chloro compounds, using potassium fluorosulfinate as a fluorinating agent, has been described (23). [Pg.161]

J. (n4-l, 5-CYCLOOCTADIENE)TETRAKIS(METHYL-HYDRAZINE)RUTHENIUM(II) BIS[HEXAFLUORO-PHOSPHATE(l -)]... [Pg.74]

N,B2RuCftnH7ft, Ruthenium(II), (nJ-l,5-cyclooctadiene)tetrakis(methyl-hydrozine)-... [Pg.427]

RuCoO,SC Ruthenium, nonacarbonyl-p.,-thio-dicobalt-, 26 352 RuCo2OuCi, Ruthenium, undecacar-bonyldicobalt-, 26 354 RuCojNOi2C 2H2(i, Ruthenate(l -), dodeca-carbonyltricobalt-tetraethylammonium, 26 358 RuF12N4P2C (,H24, Ruthenium(II), tetrakis-(acetonitrile) (n4-1,5-cyclooctadiene)-bis[hexafluorophosphate(l -)], 26 72 RuF 2NBP2Ci2H36, Ruthenium(II), (V cyclooctadiene)tetrakis(methyl-hydrazine)-... [Pg.440]

Doyle, Martin, Muller, and co-workers communicated exceptional enantiocontrol for intramolecular cyclopropanation of a series of allyl diazoacetates (Eq. 5.16) by using dirhodium(II) tetrakis(methyl 2-oxopyrrolidine-5-carboxylates), Rh2(MEPY)4, in either their R- or S-configurations [87], and they have fully elaborated these results in a subsequent report [88],... [Pg.211]

The synthesis of isomeric l,2,3,4-tetrakis(methyl-thio)hexafluoro-n-butane was finally achieved by photoassisted sonication, after the numerous attempts through the various methods had failed. A successful method described here consists of reacting trans-1,4-bis(methylth1o)hexafluoro-2-bu-tene in an excess of methyl disulfide with an added appropriate gas (hexafluoropropane) to increase and control the pressure in the reaction vessel. The heterogeneous mixture was then subjected to the combined photolysis and sonication at 50°C. The iaFNMR and mass spectral data of the product and the by-product l,2,4-tris(methylth1o)-3-H-hexafluo-ro-n-butane were presented. [Pg.287]

Chiral rhodium(II) carboxamides are exceptional catalysts for highly enantio-selective intermolecular cyclopropenation reactions (50). With ethyl diazoacetate and a series of alkynes, use of dirhodium(II) tetrakis[methyl 2-pyrrolidone-5-(R)-carboxylate], Rh2(5R-MEPY)4, in catalytic amounts ( 1.0 mol %) results in the formation of ethyl eyelopropene-3-earboxylates (eq 4) with enantiomeric excesses... [Pg.53]

J. S. Miller, and A. L. Balch, Preparation and Reactions of Tetrakis(methyl isocyanide) Complexes of Divalent Nickel, Palladium, and Platinum, Inorg. Chem. 11, 2069-2074 (1972). [Pg.286]

Structures of Tetrakis(methyl isocyanide)iron Complexes... [Pg.151]

R,5S)-(-)-6,6-DIMETH YL-3-OXABICYCLO[3.1. OJHEXAN-2-ONE. HIGHLY ENANTIOSELECTIVE INTRAMOLECULAR CYCLOPROPANATION CATALYZED BY DIRHODIUM(II) TETRAKIS[METHYL 2-PYRROLIDONE-5(R)-CARBOXYLATE]... [Pg.13]

Dirhodium(ll) tetrakis[methyl 2-pyrrolidone-5(R)-oarboxylate], Rh2(5R-MEPV)4, and its enantiomer, Rh2(5S-MEPY)4, which is prepared by the same procedure, are highly enantioselective catalysts for intramolecular cyclopropanation of allylic diazoacetates (65->94% ee) and homoallylic diazoacetates (71-90% ee),7 8 intermolecular carbon-hydrogen insertion reactions of 2-alkoxyethyl diazoacetates (57-91% ee)9 and N-alkyl-N-(tert-butyl)diazoacetamides (58-73% ee),10 Intermolecular cyclopropenation ot alkynes with ethyl diazoacetate (54-69% ee) or menthyl diazoacetates (77-98% diastereomeric excess, de),11 and intermolecular cyclopropanation of alkenes with menthyl diazoacetate (60-91% de for the cis isomer, 47-65% de for the trans isomer).12 Their use in <1.0 mol % in dichloromethane solvent effects complete reaction of the diazo ester and provides the carbenoid product in 43-88% yield. The same general method used for the preparation of Rh2(5R-MEPY)4 was employed for the synthesis of their isopropyl7 and neopentyl9 ester analogs. [Pg.22]

Dirhodium(ll) tetrakis[methyl 2-pyrrolidone-5(R)-carboxylate Rh2(5R-MEPY)4t Rhodium, tetrakis[ x-(methyl 5-oxo-L-prolinato-N1 Os)]di-, (Rh-Rh) (12) (1324-35-65-5) Thionyl chloride (8,9) (7719-09-7)... [Pg.23]

IX dimethyl ester Pyz = Pyrazine RImH = Imidazole with an R substituent on one of the carbon atoms RNC = Alkyl or aryl isocyanide (isonitrile) RNO = alkyl or aryl nitroso compound RPy = Substituted pyridine RTPP = 7 -phenyl substituted tetraphenylporphyrin TCeTPP = Tetra-/3,/3 -tetramethylenetetraphenyl-porphyrin TMINP = Tetrakis(o-(methylisonicotinamidophenyl)porphyrin) T(o-M)PyP = Tetrakis(methyl-o-pyridinium)porphyrin ... [Pg.2098]

Chiral dirhodium(II) tetrakis(methyl-2-oxopyrrolidine-5-carboxylates) and dirhodium(ll) tetrakis(4-benzyl-2-oxazolidinones) have been studied to determine factors influencing the enantiocontrol in metal-carbene transformations. Doyle et al. used the Tektronix CAChe molecular modeling system to examine the steric control on the optical yields of cyclopropanation products.Details of the force field are not available in the open literature. The low energy conformation of the proposed metal-carbene intermediate predicted absolute configurations of the product that conflicted with experiment. However, when the metal-carbene was weakly bonded to styrene, the low energy conformer... [Pg.116]

Semicorrinato)copper catalysts have also been used for intramolecular cyclopropanation reactions of alkenyl diazo ketones (eq 9 and eq 10). In this case the (semicorrinato)copper catalyst derived from complex (5) proved to be superior to related methylene-bis(oxazoline)copper complexes. Interestingly, analogous allyl diazoacetates react with markedly lower enantioselectivity under these conditions, in contrast to the results obtained with chiral Rh complexes which are excellent catalysts for intramolecular cyclopropanations of allyl diazoacetates but give poor enantioselectivities with alkenyl diazo ketones (see Dirhodium(II) Tetrakis(methyl 2-pyrrolidone-5(S -carboxylate ) Moderate enantioselectivities in the reactions... [Pg.106]

Dirhodium(II) Tetrakis(methyl 2-pyrrolidone-5(S)-carboxylate), 320 C24H38O3... [Pg.551]

Big Chemical Encyclopedia

Chemical substances, components, reactions, process design ...