Chromium complexes methyl complex

Pyrazolone, l(4-bromophenyl)-3-methyl-4-(2-methyl-6-carboxyphenylazo)-chromium complex geometrical isomerism, 6, 69 5-Pyrazolone, o-carboxyarylazo-metal complexes geometrical isomerism, 6,68... 

Pyrazolone, l-phenyl-3-methyl-4-(2-carboxyphenylazo)-chrotnium complex geometrical isomerism, 6, 68 5-Pyrazolone, l-phenyl-3-methyl-4-(2-hydroxy-4-sulfonaphth-l-ylazo)-chromium complex... 

The intramolecular cyclization route to p-lactams still provides interest. P-Amino esters (obtained by a Reformatsky-type reaction of an imine and bromoacetates derived from chiral alcohols) are cyclized by the action Grignard reagents to 4-substituted P-lactams with impressive e.e. <96TL4095>. A similar approach through a Reformatsky-type reaction uses tricarbonyl(Ti -benzaldimine)chromium complexes and ultrasound <96T4849>. 3-Methyl-azetidin-2-ones (obtained from 3-amino-2-methylpropionates) have been resolved and their... 

CHROMIUM TRIOXIDE-PYRIDINE COMPLEX, preparation in situ, 55, 84 Chrysene, 58,15, 16 fzans-Cinnamaldehyde, 57, 85 Cinnamaldehyde dimethylacetal, 57, 84 Cinnamyl alcohol, 56,105 58, 9 2-Cinnamylthio-2-thiazoline, 56, 82 Citric acid, 58,43 Citronellal, 58, 107, 112 Cleavage of methyl ethers with iodotri-methylsilane, 59, 35 Cobalt(II) acetylacetonate, 57, 13 Conjugate addition of aryl aldehydes, 59, 53 Copper (I) bromide, 58, 52, 54, 56 59,123 COPPER CATALYZED ARYLATION OF /3-DlCARBONYL COMPOUNDS, 58, 52 Copper (I) chloride, 57, 34 Copper (II) chloride, 56, 10 Copper(I) iodide, 55, 105, 123, 124 Copper(I) oxide, 59, 206 Copper(ll) oxide, 56, 10 Copper salts of carboxylic acids, 59, 127 Copper(l) thiophenoxide, 55, 123 59, 210 Copper(l) trifluoromethanesulfonate, 59, 202... 

Moffett [179] determined chromium in seawater by Zeeman corrected graphite tube atomisation atomic absorption spectrometry. The chromium is first complexed with a pentan-2,4 dione solution of ammonium 1 pyrrolidine carbodithioc acid, then this complex extracted from the water with a ketonic solvent such as methyl isobutyl ketone, 4-methylpentan-2-one or diisobutyl ketone. 

In reactions carried out for 24 h at room temperature, a 95% yield of cyclo-hexanol from cyclohexanone was obtained. Other ketones and aldehydes were also hydrogenated under identical conditions, but with slower rates (38% conversion for hydrogenation of 2-hexanone, 25% conversion of acetophenone, 45% for 3-methyl-2-butanone). Insertion of the C=0 bond of the ketone or aldehyde into the Cr-H bond was proposed as the first step, producing a chromium alk-oxide complex that reacts with acid to generate the alcohol product. The anionic chromium hydride [(COJsCrH]- is regenerated from the formate complex by... 

Experimental Procedure 2.2.8. [4 + 3] Cycloaddition of a Chromium Vinyl-carbene Complex to a 1-Azadiene rra/w-4-(2-Furyl)-2-methoxy-5-methyl-4,5-dihydro-3H-azepine... 

The reaction is catalyzed by a group VIII metal species, particularly that of rhodium or palladium. The initial metal species may be any variety of complexes (e.g., PdCl2 Pd acetate, etc.). A source of halide is necessary iodide is especially effective. The most convenient source is methyl iodide, since it is likely a reaction intermediate. In addition, an organic promoter must be included for catalytic activity. These promoters are generally tertiary phosphines or amines. Also, chromium complexes were found to have an important promotional effect. 

The following procedure can be extended to prepare l-oxacyclopent-2-ylidene chromium complexes substituted in the 3 or 5 position.4 Thus the reaction of the anion of pentacarbonyl(l-methoxypropylidene)chromium(0) with ethylene oxide gives pentacarbonyl [dihydro-3-methyl-2(3//)-furylidene] chromium(O) [pentacarbonyl(3-methyl-l-oxacyclopent-2-ylidene)chromium(P)], and the reaction of the anion of pentacarbonyl(l-methoxyethylidene)chromium(0) with propylene oxide gives pentacarbonyl(dihydro-5-methyl-2(3//)-furanylidene)-chromium(O) [pentacarbonyl(5-methyl-l-oxacyclopent-2-ylidene)chromium(0)]. 

Some further examples of stereoselective deprotonation/alkylation reactions of tricarbonyl-chromium complexed (V-methyl tetrahydroisoquinolines have been reported27. Starting with the enantiomerically pure (35)-methyl tetrahydroisoquinoline reaction with hexacarbonyl-chromium led to a mixture of endo- (40%) and exo- (60%) complexes, which were deprotonated with butyllithium and subsequently methylated with iodomethane. In this way methylation occurred firstly at the 4- and secondly at the 1-position. In all cases, the methyl group entered anti to the chromium complexed face. After separation of the alkylated complexes by chromatography and oxidative decomplexation, the enantiomerically pure diastereomers (—)-(l 5,35,47 )-and ( + )-(17 ,35,45)-1,2,3,4-tetrahydro-l,2,3,4-tetramethylisoquinolme were obtained, benzylic amines such as tetrahydroisoquinoline to 2-amino-4,5-dihydrooxazoles. Deprotona... 

C2H,N, Pyridine, 3,5-dimethyl-palladium complex, 26 210 CbHsNO, Benzoyl isocyanide chromium com-C HbO, Ethanone, 1-phenyl-manganese complex, 26 156-158 CBH, 02, Methyl benzoate chromium complex, 26 32 C H i, o-Xylylene magnesium complex, 26 147 ChH P, Phosphine, dimethylphenyl-iron complex, 26 61 ruthenium complex, 26 273 ChH12, 1,5-Cyclooctadiene iridium complex, 26 122 ruthenium complexes, 26 69-72, 253-256 ChH OjPS, 2-Butenedioic acid, 2-(dimethylphosphinothioyl)-dimethyl ester, manganese complex, 26 163... 

NO, Nitrosyls, molybdenum and tungsten, 26 132, 133 NOC, Cyanate tungsten complex, 26 42 NOC4H7, 3-Butenamide nickel complex, 26 206 NOC4H , 2-Propenamide, 2-methyl-nickel complex, 26 205 NOC H, Benzoyl isocyanide chromium complex, 26 32, 34, 35 N04ReC16H, Perrhenate, tetrabutylam-monium, 26 391... 

OiCsHm, Propanoic acid, 2,2-dimethyl-tungsten complex, 26 223 02C Hh, Methyl benzoate chromium complex, 26 32 02CuiH (, 2,3-Naphthalenediol in prepn. of cu-tetraamminedihaloruthe-nium(III) complexes, 26 66, 67... 

Chromium(III) complexes of a number of polyhydroxamic acids, microbial iron sequestering and transport agents (siderochromes) have been reported.797,798 The kinetic inertness of the chromium(III) complexes allows the facile separation of isomers for the model complex tris(iV-methyl-( - )-methoxyacetylhydroxamato)chromium(III), D-cis, L-cis and the l/d-trans isomers have been separated.798 The chromium complexes of desferrioxamine B (191) have been investigated the possible isomers are illustrated below (192-196). The cis isomer was isolated in relatively pure form.799 Thiohydroxamate800 and dihydroxamate (rhodotorulic acid) complexes have also been studied.801... 

Cyclopropylalkoxycarbene complexes are much less reactive towards nucleophilic reactions. The methoxy chromium complex does, however, react with iodine to give directly methyl 4-iodobutyrate, derived by hydrolysis of the expected diiodovinyl ether (equation 78)139. 

Methyl (trifluoromethylsulfonyl)-methyl sulfone, 193 Tributyl(iodomethyl)tin, 314 Reduction of 1,3-dienes to monoenes Arene(tricarbonyl)chromium complexes, 19... 

Support for Schetty s postulates has been provided by X-ray crystal structure determinations. Thus the 2 1 chromium complexes (126) and (127) of the two o,o -dihydroxydiarylazo compounds 2,2 -dihydroxyazobenzene and l-(2-hydroxy-4-nitrophenylazo)-2-naphthol, respectively, have been proved89 to have meridional configurations, whilst the 2 1 chromium complex (128) of the o-carboxyarylazopyrazolone l-(4-brornophenyl)-3-methyl-4-(2-methyl-6-carboxyphenylazo)-5-pyrazolone has been proved90 to have a facial configuration. 

A similar argument can be applied to the results of later work by Idelson et al.i9 In this they prepared the chromium complex (133) by interaction of the 1 1 chromium complex of 1-phenyl-3-methyl-4-(2-hydroxy-4-cyanonaphth-l-ylazo)-5-pyrazolone and diethylenetriamine and by reaction of the azo compound with [Cr(CO)3dien]. Identical products were obtained and, since the diethylenetriamine occupies9 a facial position in [Cr(CO)3dien], it was concluded that the complex (133) had a facial configuration. Similarly, the reported77 separation of isomeric 2 1 chromium complexes of 2-amino-6-(2-hydroxy-6-nitro-4-sulfonaphth-l-ylazo)-5-naphthol-7-sulfonic acid is... 

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