Oxidations copper® bromide

In the improved synthesis of Ifetroban described above, environmental concerns due to special handling of copper bromide waste and hazards associated with hexa-methylene tetramine (HMT) on manufacturing scale led to further perfection of the synthesis. Mechanistic considerations suggested that an oxidized form of aminoamide B (Scheme 4) would eliminate the necessity for a late-stage copper-mediated oxidation. This was indeed accomplished. The cyclization-elimination sequence was initiated by a Lewis acid and completed by base-mediated elimination to afford the Ifetroban penultimate. In addition to eliminating the need for copper bromide and HMT, this modification helped to reduce the cost of the product by an additional 15%. 

The reaction of o-nitrobenzaldehydes with some benzene derivatives in the presence of strong acid (H2S04, PPA) is a classical synthesis of acridinol N-oxides (373) (37BSF240) The synthesis works for benzyl alcohol, benzene, toluene and halobenzenes, but not for benzoic acid, benzonitrile, dimethylaniline, or nitrobenzene. Isoquinoline N-oxides (374) have been obtained from o-bromobenzaldoxime or the acetophenone derivative, and active methylene compounds with copper bromide and sodium hydride (77S760). The azobenzene cobalt tricarbonyl (375) reacts with hexafluorobut-2-yne to give a quinol-2-one (72CC1228), and the 3,4,5-tricyanopyridine (376) is formed when tetracyanoethylene reacts with an enaminonitrile (80S471). 

Under the influence of oxidizing systems [copper bromide - CC1J these systems are oxidized into the corresponding 1,3,5-trinitrobenzene derivatives, whereas in the presence of the same system and crown esters (e.g., 18-crown-6) 4,6-dinitroan-thranils are formed (Scheme 2.65). So, the presence of the group in the geminal center of the o-complex is a necessary condition for conversion of this type [435],... 

In the same year we achieved the synthesis of the enantiomers of 110, as shown in Figure 4.61.107 (5)-Citronellal was converted to olefinic ester A, which was epoxidized to give B. Treatment of B with isopropylmagnesium chloride in the presence of copper bromide furnished lactone C, which afforded diol D by treatment with methylmagnesium bromide. Finally, Dess-Martin oxidation of D yielded (S)-stigmolone (110), which was in equilibrium with (2R,3S)-1S. Similarly, (7 )-citronellal afforded (7 )-110. ... 

Imidazole /V-oxide substrates may be used in a similar fashion. Initial investigations revealed that the use of palladium acetate in conjunction with an electron deficient 4-fluorophenylphosphine in acetonitrile at 70 °C provides C2 arylation in high yields. With the goal of achieving the same reactivity at or near room temperature it was determined that the use of palladium acetate in conjunction with a Buchwald ligand, catalytic copper bromide and 30 mol% pivalic acid in acetonitrile could also achieve high yields of C2 arylation at 25 °C. As was the case with thiazole V-oxides. if the C2 and C5 positions of the imidazole are blocked C4 arylation may also be achieved in synthetically useful yield (Scheme 15). 

COPPER BROMIDE (7789-45-9) BFjCu Aqueous solution is an acid. Incompatible with bases, inducing amines, amides, and inorganic hydroxides strong oxidizers, including chlorine, fluorine, peroxides and hydroperoxides potassium. 

PROPARGYL BROMIDE (106-96-7) Forms explosive mixture with air (flash point 50°F/10°C). Elevated temperatures above 425°F/218°C can cause deflagration. A shock-, impact-, and heat-sensitive material that should be treated and stored as an explosive unless stabilized or diluted with toluene, which lowers the flash point slightly (39°F/4°C 25% solution), but renders it less sensitive. Forms shock-sensitive explosive compound with chloropi-crin. Violent reaction or explosion on contact with oxidizers, copper, its alloys, mercury, or silver. Flow or agitation of substance may generate electrostatic charges due to low conductivity. 

Caprolactone (CL) (Acros, 99%) was dried over calcium hydride at r.t. for 48h and then distilled under reduced pressure. 2-(N,N-dimethylamino)ethyl methaciylate (DMAEMA) (Aldrich, 98%) was deprived of its inhibitor by filtration through a basic alumina column, and depending on samples (see text) dried over calcium hydride at r.t. for 24h and then distilled under reduced pressme. Butane-1,4-diol (Acros, > 99%) was dried over calcium hydride for 48h at r.t. and distilled at 70°C under reduced pressure. Triethylamine (NEts, Fluka, 99%) was dried over barium oxide for 48h at r.t. and distilled under reduced pressure. Copper bromide (CuBr, Fluka, 98%) was purified in acetic acid and recrystallized in ethanol under inert atmosphere until a white powder is obtained. Tin(ll) bis-2-ethyl hexanoate (Sn(Oct)2, Aldrich, 95%), methacrylic anhydride (Aldrich, 94%), N,N-dimethylamino-4-pyridine (DMAP, Acros 99%), 1,1,4,7,10,10-hexamethyltriethylene tetramine (HMTETA, Aldrich, 97%), ethyl-2-bromoisobutyrate (E BBr, Aldrich, 98%), N,N-dicyclohexylcarbodiimide (DCC, Acros, 99%), were used as received. Tetrahydrofuran (THF, Labscan, 99%) was dried over molecular sieves (4A) and distilled over polystyryl lithium (PS LC) complex under reduced pressure just before use. Toluene (Labscan, 99%) was dried by refluxing over CaH2. 

The ring synthesis of the tetrahydro-1,3-azoles is simply the formation of N,N-, N,0-or A, S-analogues of aldehyde cyclic acetals the ring synthesis of the 4,5-dihydro-heterocycles requires an acid oxidation level in place of aldehyde. A good route to the aromatic systems is therefore the dehydrogenation of these reduced and partially reduced systems. Nickel peroxide, " manganese(IV) oxide, copper(II) bromide/ base, and bromotrichloromethane/diazabicycloundecane have been used. The example shown uses cysteine methyl ester with a chiral aldehyde to form the tetrahydrothiazole. 

Cuprobam. See Tricopper dichloride dimethyidithiocarbamate Cuprophenyl black BWL. See Direct black 114 Cuprous bromide. See Copper bromide (ous) Cuprous chloride. See Copper chloride (ous) Cuprous cyanide. See Copper cyanide Cuprous dichloride. See Copper chloride (ous) Cuprous iodide. See Copper iodide (ous) Cuprous oxide Cuprous oxide, red Cuprous oxide, yellow. See Copper oxide (ous) Cuproxat. See Copper sulfate, tribasic... 

Ethylaluminum dichloride Ethylaluminum sesquichloride Tetrabutyl titanate Tetraisopropyl titanate Triethylborane Trimethylaluminum catalyst, olefin polymers Tungsten hexachloride catalyst, olefin/diene polymerizationscatalyst olefin polymerizations Tri-n-hexylaluminum catalyst, olefinic addition Methanesulfonic acid catalyst, one-component RTV s Dibutyltin diisooctylmaleate catalyst, organic compounds chlorination Manganese chloride (ous), tetrahydrate catalyst, organic reactions Beryllium oxide Chromium oxide (ic) Copper bromide (ous) Copper phosphate (ic) Ferric chloride... 

Finally, the combination of copper bromide as oxidant and ureas as nitrogen source enabled an intramolecular palladium catalyzed diamination of acrylates (Scheme 4.13) [37]. For methyl or ethyl esters, this process proceeds with excellent diastereoselectivity in favor of the syn-configured cyclic urea product... 

The oxidative coupling of benzothiazoles with azine JV-oxides is promoted by catalytic Pd(OAc)2 and CuBr and stoichiometric Cu(OPiv)2 (eq 142). The copper pivalate salt plays a dual role oxidant and concerted metalation-deprotonation (CMD) promoter, while the role of copper bromide is less obvious. 

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