Imines, acetylation salts

When the 1-monoximes or dioximes of 4-acetyl-l-tetralones are hydrogenated in the presence of palladium, mixtures of diastereoisomeric 1-aminotetralones are formed. The m-aminoketone isomers readily form dehydrobenzoisoquinuclideines (3,4-disubstituted-1,4-dihydro-1,4-ethano-isoquinolines). Quaternary immonium salts prepared from these bicyclic imines are then converted by bases to bicyclic enamines [2,4-disubstituted-3-alkylidene-1,4-ethano-1,2,3,4-tetrahydroisoquinolines (25)]. 

N-silylated imines 509 react with the Li salts of tosylmethylisonitriles to give 4,5-disubstituted imidazoles in moderate yields [93]. Acetylation of N-trimethylsilyl imines 509 with acetyl chloride and triethylamine affords 72-80% of the aza-dienes 510 these undergo readily Diels-Alder reactions, e.g. with maleic anhydride at 24 °C to give 511 [94] or with dimethyl acetylenedicarboxylate to give dimethyl pyridine-3,4-dicarboxylates [94] (Scheme 5.29). 

Lastly, Livinghouse s approach to the tricyclic core of 4 is highlighted by an acylnitrilium spirocyclization [19d], Exposure of isonitrile 48 to thiophenyl acetyl chloride provides an intermediate chloramine (49) that, in the presence of a silver salt, eliminates the chloride to form a nitrilium ion (R-N = C+-R). The nitrilium is attacked by the nucleophilic aromatic ring to furnish spirocyclic imine 50 in high... 

The reaction of l-benzyl-4-(acetylimido)-l/7-[l,2,4]triazolium inner salt 120 (an azomethine imine) with aromatic isothiocyanates yields among other products 5-acetyl-6-(arylimino)-l,5,6,7-anhydro[l,2,4]triazolo[3,4-A][l,3,4]thiadia-zoles 121 (Equation 34) <1984CCC1713>. 

The A-acetyl derivatives of the 2-alkylthio-l,3-thiadiazol-4-imines (124, R = SR, R = Ac) undergo nucleophilic displacement reaction with amines (benzylamine, cyclohexylamine, morpholine, or aniline) giving the 2-amino derivatives (124, R = NRj, R = Ac). The salt (126, R = R = Ph, R = R = H, X = Cl) reacts with aniline at room temperature giving 4-anilino-2-phenyl-l,3-thiazole (128), presumably by a mechanism involving cleavage of the heterocyclic ring. ... 

Oximes, Tosylhydrazones, and Related Derivatives.—Ketoximes afford enimides in refluxing acetic anhydride-pyridine.181 Theproduct (207) from 5a-cholestan-3-one oxime (206), for example, gave 3-acetylamino-5a-cholest-2-ene (208) in 93% yield after chromatography on alumina. Use of succinic instead of acetic anhydride, with pyridine, gave the enimide (209) which was stable to chromatography. A radical mechanism is proposed. Reduction of ketoximes by Cr11, V11, or Tiin salts in acetic anhydride affords the same enamides, by acetylation of the intermediate imines. The... 

Pyrazole rings are formed from 2-alkylpyridine-Af-imines and acid chlorides under basic conditions. For example, the 1-aminopyridinium salt (336) gives first (337) but this is very reactive and is acetylated under the reaction conditions to (338 Scheme 95) (68JOC3766). The 2-hydroxymethylpyridine (339) shows similar reactions (Scheme 96) (73CPB2146). 

Low-valent metal salts have been used to bring about reductive cleavage of oximes. Corey and Rich-man used chromium(II) acetate to convert O-acetyl ketoximes into imines, which were hydrolyzed to ketones. " Aqueous titanium(III) chloride and vanadium(II) salts also reduce oximes again, the imines are usually hydrolyzed in situ, but some hindered imines, such as compound (37), are isolable." A method of preventing hydrolysis is to carry out the reduction in anhydrous conditions in the presence of an acylating agent. The products of such reactions, when applied to oximes of enolizable ketones, are en-amides. For example, these ketoximes are converted into A/-formylenamines when heated in acetonitrile with anhydrous titanium(III) acetate and acetic formic anhydride cyclohexanone oxime gives the en-amide (38 97% Scheme 22)." This type of reduction has been used by Barton and coworkers to prepare enamides from steroidal oximes. They reported that the reaction could be performed by acetic... 

This enol reacts with the imine salt we have previously made and it will be easier to see this reaction if we redraw the enol in a different conformation. The imine salt does not have to wait around for acetoacetyl CoA to be made. The cell has a good stock of acetyl CoA and its condensation product. 

Poly(ethylene oxide) is a linear polymer containing the donor oxygen atoms in the main backbone. Some other similar systems known to function as polymer electrolytes include simple poly ethylene glycol (PEG) [145], end acetylated PEG [146], poly propylene oxide (PPO) [ 147-148], poly(/ -propiolactone) [149], polyethylene succinate) [150-151],poly (ethylene adipate) [152],poly (ethylene imine) [153] and poly (alkylene sulfide) [154], Many of these form metal salt complexes. However, conductivities of the order of 10 s S cm are observed only at high temperatures. Table 5 summarizes this data. 

Sulphonedi-imines are sufficiently nucleophilic to displace halogen from reactive halides. Thus, reaction with CICN in the presence of triethylamine afforded the mono- or bis-cyano-derivative depending on the molar ratio of reactants used. The bis-cyano-derivative (119) was not sufficiently nucleophilic to form salts in the presence of acid. Acid hydrolysis afforded the bis-amide, and treatment with acetyl chloride in aqueous acetonitrile... 

Organic and Analytical Chemistry. As mentioned previously, Dubsky was trained in organic chemistry during his sti in Leyden and Groningen. At Leyden he studied acetylation and nitration, especially of imines, which resulted in several papers (5 ). At the same time he extensively studied diketopiperazines, publishing a series of fourteen papers on these compounds 39). At Groningen Dubsky devoted his effort to the sulfonation of carboxylic acids 40), resulting in his interest in metal salts of acids sulfonated in the a-position 41). 

Functionalized iminium salts 24 can be readily prepared by a number of methods and allows the reaction to be conducted at lower temperatures and in non-protic solvents thus allowing other, more sensitive active hydrogen species to participate in this reaction. These methods can include alkylation of existing imine 22, cleavage of aminals 25 or hemi-aminals 23 with acetyl chloride or trimethylsilyl iodide/chloride, or in a direct fashion from carbonyl derivative 26 with amine salts or with trimethylsilyl amines. 

Alditol-l-yl substituted pyrroles or pyrazoles (e.g. 88 and 89) were obtained by addition to per-<7-acetylated 1,2-dideoxy-l-nitro-D- a/acm- and D-manno-l-hep-tenitols of the sodium salt of tosylmethyl isocyanide or the zwitterionic diaryl nitrile imines (e.g. PhC=N -N Ph), respectively. A general one-pot synthesis of alditol-l-yl substituted imidazoles (e.g. 90) involved reaction of aldoses with... 

An interesting D-ring closure was used by Pakrashi and his coworkers to synthesize normalindine (466) and norisomalindine (467) (Scheme 3.81) (130). Imine 462, prepared by condensation of tryptamine and 3-acetylpyridine, was reduced and the formed amine was acetylated to afford amide 463. Bischler-Napieralski cyclization of 463 provided tetracyclic iminium bis-perchlorate salt 464 which when treated with triethylamine and pivaloyl chloride underwent a second cyclization to yield the pentacyclic enamine 465. Reduction of the olefinic group in 465 afforded the desired azayohimbines, 466 and 467. 

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