Nickel trifluoroacetates

The polymerization rate depends on the nature of the 7r-allylic grouping attached to the initial catalyst and there does not appear to be an acceleration stage corresponding to a slow initiation step followed by a faster propagation reaction [248], which would have been expected. Values for fep (1 mole sec at 30°C) and activation energies (kcal mole ) for ir-allyl, ir-methallyl and ir-crotyl nickel trifluoroacetates are 1.2 X 10 3 and 12.2, 1.66 x 10 and 10.7 and 4.3 x 10 and 10.2, respectively. 

The nickel trifluoroacetates NiL4(OCOCF3)2 (L = / -, y-picoline, / -, y-ethylpyridine) undergo slow cis-trans isomerization at room temperature (in contrast to the cobalt complexes, see p. 69), the major isomer in each case absorbing in the range 8 —25 to —34, and the minor, sometimes not detectable, in the range 8 +10 to +20. (176)... 

Catalysts which lead to cis polymer show a significantly higher stereoselectivity in the bond forming reaction. When (ir-allyl nickel iodide)2 modified with TiCl is employed, the 1, 2 deuterium stereochemistry is 70% dl, and 30% meso as revealed by analysis of succinic anhydride. In addition, monomer isomerization is extensive, and could account for a large fraction of the meso structures which are formed, j ke use of (ir-allyl nickel trifluoroacetate)2 as catalyst led to a similar result (32% meso), accompanied by little if any monomer isomerization. Thus, it appears that in reactions to form cis polymer, some, but not always all, of the stereochemical information present in the starting diene is preserved in the polymer. In contrast, none of the initial diene stereochemistry can be detected in the trans polymer. 

The "equibinary" l,4-cis/l,4-trans polybutadiene prepared using a n-allyl nickel trifluoroacetate catalyst [70,71,96,97] and the polybutadiene obtained by polymerization of cyclooctadiene using an olefin metathesis catalyst system where shown by nmr to have random distributions of cis- and trans-ianits, although there is some indication that "equibinary" copolymers with non-Bernoullian structures are obtained in some cases [96]. Polybutadienes prepared using alkyl lithium initiators in hydrocarbon solvents have also been shown to have random distributions of 1,4-cis and 1,4-trans units [20,23,71,90]. 

Treated with trifluoroacetic anhydride, sulfoxides 218 undergo conversion to triazapentalenes 219 with high yields. The process must involve acylation of the sulfoxide oxygen atom and generation of a carbocation that attacks the N-2 atom of benzotriazole. Hydrogenation over Raney nickel cleaves the C-S and one of the N-N bonds to generate >rtfe -substituted anilines 220 (Scheme 27) <2002EJ0493>. 

The formation of cationic nickel hydride complexes by the oxidative addition of Brdnsted acids (HY) to zero-valent nickel phosphine or phosphite complexes (method C,) has already been discussed in Section II. Interesting in this connection is a recent H NMR study of the reaction of bis[tri(o-tolyl)phosphite]nickelethylene and trifluoroacetic acid which leads to the formation of a square-planar bis[tri(o-tolyl)phosphite] hydridonickel trifluoroacetate (30) (see below) having a cis arrangement of the phosphite ligands (82). 

GABA HMG-CoA HMPA HT LDA LHMDS LTMP NADH NBH NBS NCS NIS NK NMP PMB PPA RaNi Red-Al RNA SEM SnAt TBAF TBDMS TBS Tf TFA TFP THF TIPS TMEDA TMG TMP TMS Tol-BINAP TTF y-aminobutyric acid hydroxymethylglutaryl coenzyme A hexamethylphosphoric triamide hydroxytryptamine (serotonin) lithium diisopropylamide lithium hexamethyldisilazane lithium 2,2,6,6-tetramethylpiperidine reduced nicotinamide adenine dinucleotide l,3-dibromo-5,5-dimethylhydantoin A-bromosuccinimide A-chlorosuccinimide A-iodosuccinimide neurokinin 1 -methyl-2-pyrrolidinone para-methoxybenzyl polyphosphoric acid Raney Nickel sodium bis(2-methoxyethoxy)aluminum hydride ribonucleic acid 2-(trimethylsilyl)ethoxymethyl nucleophilic substitution on an aromatic ring tetrabutylammonium fluoride tert-butyldimcthyisilyl fert-butyldimethylsilyl trifluoromethanesulfonyl (triflyl) trifluoroacetic acid tri-o-furylphosphine tetrahydrofuran triisopropylsilyl A, N,N ,N -tetramethy lethylenediamine tetramethyl guanidine tetramethylpiperidine trimethylsilyl 2,2 -bis(di-p-tolylphosphino)-l,r-binaphthyl tetrathiafulvalene... 

M[pz(A4)] A = S2ML2. The octakis(.V-R)porphyra/,ines reported by Schramm and Hoffman (2), M[pz(S-R)8 (M = Ni, Cu), (60), can be converted to the octathiolate M[pz(S )g] (Scheme 11) via reductive cleavage of the sulfur-carbon bond when R = benzyl (Bn), and this tetra-bis(dithiolate) can then be peripherally capped with metal-ligand systems to yield peripherally tetrametalated star porphyrazines. The benzyl dinitrile 57 can be macrocyclized around magnesium butoxide to form [Mg[pz(S-Bn)8] (58) (35-40%), which can then be demetalated with trifluoroacetic acid to form 59 (90%), which is subsequently remetalated with nickel or copper acetate to form 60a (95%) and 60b (70%) (Scheme 11) (3, 23, 24). Deprotection of 60a or 60b with sodium in ammonia yields the Ni or Cu tetra-enedithiolates, 61a or 61b to which addition of di-ferf-butyl or n-butyl tin dinitrate produces the peripherally metalated star porphyrazines 62a (37%), 62b (80%), and 62c (41%). 

Synthesis. These macrocycles are prepared from seven-membered ring dinitrile complexes, 84a-84c (Scheme 17), which contain either methylene, sulfur or oxygen in the five position (129). These cyclic dinitriles are synthesized by alkylating maleonitrile dithiolate or derivatives thereof with the corresponding dihalide. The dinitriles 84a-84c can be cyclized in magnesium propoxide to form porphyrazines 85a (33%), 85b (19%), and 85c (27%) (Scheme 17), which can be demetalated with trifluoroacetic to form 86a-86c. Additionally, 86a has been remetalated with nickel (87a, 92%), copper (88a, 95%), and zinc (89a, 94%). The sulfur and oxygen derivatives 85b, 85c, 86b, and 86c are of low solubility and are not suitable for further manipulation. 

Analogously, complex 218 was prepared by mixed macrocyclization of 2,5-diiminopyrrolidine (213) with ferf-butylphenylpyrroline (68) in 19% yield. The free base (219) (95%) was obtained by demetalation of magnesium complex 218 with trifluoroacetic acid and subsequent remetalation of 219 with Ni(OAc)2 gave the corresponding nickel complex 220 in 98% yield. 

The addition of iodine trifluoroacetate (produced by reaction of iodine with silver trifluoroacetate) to unsaturated carbohydrates has been investigated.134 Treatment of 5,6-dideoxy-l,2-0-isopropylidene-a-D-xylo-hex-5-enofuranose (89) with silver trifluoroacetate and iodine in acetonitrile gave 3,6-anhydro-5-deoxy-5-iodo-l,2-0-iso-propylidene-a-D-gluco(and /3-L-ido)furanose (91) and 5-deoxy-5-iodo-l,2-0-isopropylidene-6-0-(trifluoroacetyl)-o -D-gluco(and/or /3-L-ido)-furanose (92), with the former preponderating. Component 91 was converted into 3,6-anhydro-5-deoxy-l,2-0-isopropylidene-a-D-xj/io-hexofuranose (94) by hydrogenation over Raney nickel (see also, Section III,3 p. 299), and component 92 was converted into 5-deoxy-l,2-0-isopropylidene-a-D-xy/o-hexofuranose (95) by treat-... 

Reduction of derivatives of ally lie alcohols. Nickel boride can effect reduction of allylic alcohols to alkenes, but yields are generally improved by reduction of the acetates, benzoates, or trifluoroacetates.1 Reduction of allylic benzyl ethers to alkenes is effected in higher yield with Raney nickel. Methyl ethers are not reduced by either reagent. The trimethylsilyl ethers of allylic alcohols are reduced to alkenes by nickel boride in diglyme.2... 

BIPHENYLS Bis(l,5-cyclooctadiene)nickel. Tetrakis(triphenylphosphine)palladium. Thallium(III) trifluoroacetate-Palladium(Il) acetate. Titanium(IV) chloride. 

Chloroacetic acid Oxalyl chloride Trifluoroacetic acid Hydrogen chloride Nickel Raney Lithium hydroxide... 

Tetraphenylporphine (1 g, 1.63 mmole) is dissolved in a minimum volume of trifluoroacetic acid (about 15 mL) and the solution is added to glacial acetic acid (200 mL) that has been heated at reflux in a 500-mL, round-bottomed flask. Nickel diacetate tetrahydrate (2 g, 8.0 mmole) is dissolved in a minimum of hot acetic acid and the resulting solution is added dropwise over a period of 5 minutes to the refluxing tetraphenylporphine solution. The mixture is allowed to heat at reflux for a further hour, and the hot solution is then filtered. The product is washed with boiling acetic acid until the filtrate is colorless and then further washed with water (3 X 25 mL) and methanol (3 X 25 mL). The purple crystalline product is dried in vacuum to give 1.05 g (96%). Anal. Calcd. for C44Hj8N4Ni C, 78.71 H, 4.20 N, 834. Found C, 79.05 H, 432 N, 8.22. 

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