Aroyl salts

The work reported here is the last experimental study of the Keele Polymer Group which came to an end in 1985. The senior author believes that he has achieved one of his principal chemical objectives, to determine some credible kp values and to discover the optimum conditions. He hopes that others will adopt the use of highly polar solvents and will explore a wide temperature range. For low temperatures, the eutectic mixtures of PhN02 with one of the nitronaphthalenes or dinitrobenzenes will be needed. Another useful, highly polar, solvent is S02. The nitroalkanes should be avoided. The initiator of choice should be an aroyl salt of a stable anion, and it is clear that the ideal such salt has not yet been found, but useful guidelines for finding improved initiators (in terms of speed of reaction, shelf-life and solubility) are available [21]. 

Similarly, 5-thiazole alkanoic acids and their salts are obtained from thioamides and /3-halo -y-keto acids (695). Thus thioarylamides condensed with 3-aroyl-3-bromopropionic acid (88) in isopropanolic solution in the presence of Na COs give first 4-hydroxy-2-aryl-A-2-thiazoline-5-acetic acid intermediates (89), which were dehydrated in toluene with catalytic amounts of p-toluene sulfonic acid to 2,4-diaryl-5-thiazole acetic acid (90) (Scheme 39) (657), with R = H or Me Ar = Ph, o-, m- or p-tolyl, o-, m-, or P-CIC6H4, 0-, m-, or p-MeOC(iH4, P-CF3C6H4, a-thienyl, a-naphthyl (657). 

The synthesis of 3-acyl- and 3-aroyl-l,2-benzisoxazoles was accomplished by the desulfurization of (562). The dithioacetal (562) was prepared by the addition of the lithium salt of propenedithioacetal to an isocyanate with subsequent base cyclization (equation 61) (B-79MI41609). 

Jap-KIingermarm reactions, 4, 301 oxidation, 4, 299 reactions, 4, 299 synthesis, 4, 362 tautomerism, 4, 38, 200 Indole, 5-amino-synthesis, 4, 341 Indole, C-amino-oxidation, 4, 299 tautomerism, 4, 298 Indole, 3-(2-aminobutyl)-as antidepressant, 4, 371 Indole, (2-aminoethyl)-synthesis, 4, 278 Indole, 3-(2-aminoethyl)-synthesis, 4, 337 Indole, aminomethyl-reactions, 4, 71 Indole, 4-aminomethyl-synthesis, 4, 150 Indole, (aminovinyl)-synthesis, 4, 286 Indole, 1-aroyl-oxidation, 4, 57 oxidative dimerization catalysis by Pd(II) salts, 4, 252 Indole, 1-aroyloxy-rearrangement, 4, 244 Indole, 2-aryl-nitration, 4, 211 nitrosation, 4, 210 synthesis, 4, 324 Indole, 3-(arylazo)-rearrangement, 4, 301 Indole, 3-(arylthio)-synthesis, 4, 368 Indole, 3-azophenyl-nitration, 4, 49 Indole, 1-benzenesulfonyl-by lithiation, 4, 238 Indole, 1-benzoyl photosensitized reactions with methyl acrylate, 4, 268 Indole, 3-benzoyl-l,2-dimethyl-reactions... 

Our experimental results (Table 1) showed that this approach does work for the series of alkoyl salts but it fails to predict the considerably greater solubilities of the aroyl and aryl salts which are also shown in Table 1. 

Choice of a very rapidly initiating cation, e.g., an aroyl or diarylmethylium salt, to avoid the complication from slow initiation. 

The reaction of sodium azide with N-aryl chloroimines, obtained from benzanilides and thionyl chloride, to form 1,5-disubstituted tetrazoles is catalysed by tetra-n-butyl-ammonium bromide (Scheme 5.26, Table 5.40) [18] in variable yields, but generally <85%. 5-Butyl-2,3-diphenyltetrazolium salts have also been used as catalysts [18, 19]. 1,5-Disubstituted tetrazoles are also obtained from a one-pot sequential reaction of carbodimides with sodium azide and an aroyl chloride in the presence of tetra-n-butylammonium chloride [20]. 5-Chlorotetrazoles are obtained from the catalysed reaction of aryldichloroisocyanides with sodium azide (Scheme 5.26) [21],... 

In the 1,2,4-triazole series, base-induced degenerate rearrangements have been reported with the aroylarylazo-l,2,4-triazolium salts 185 (87MI3) (Scheme IV.72). The reaction product is 3-aroyl-l-aryl-1,2,4-triazole 187, and its formation can be described as involving an ANRORC mechanism, initiated by an addition of the nucleophile at C-5, ring opening into 186, and subsequent heterocyclization with the former CNN side chain of the rearranging 1,2,4-triazole. 

Schmidt showed that reaction of 1 mole of aroyl chloride with 2 moles of an aryl nitrile in the presence of stannic or zinc chloride afforded in excellent yields a 2,4,6-triaryldiazapyrylium salt (109) in which at least two of the aryl groups (at positions 2 and 4) were alike. It was presumed that the intermediate was an aroylnitrilium ion (108). 

The reduction of aroyl chlorides take a different course in the presence of Ni(ll) salts. Reaction is best effected in an undivided cell with a nickel anode and a nickel foam cathode with acetonitrile containir tetrabutylammonium fluoroborate as electrolyte. Symmetrical ketones are formed [173], Substimted benzoyl chlorides yield the benzophenone in 47-72% yields. Phenacetylchloride also gives the ketone in good yield but in general, alkanoyl chlorides do not react. 

Crystallisable salts and related compounds. Almost all crystallisable catalysts, such as sodium and lithium aromatic compounds (e.g. sodium naphthalide), -oyl salts such as aroyl hexafluorophosphates, alkoxides, and many others can be prepared in a vacuum system and then purified by repeated crystallisations and washings in a closed system (see Chapter 5) thereafter they can be distributed into breakable phials or other devices as described in Chapter 3. 

Aroyl and related salts (ArCO, AlkCO ) and stable carbenium ion salts (e.g. Ar3C ) of complex anions MtX . i can be synthesised essentially by two routes, silver salt double decomposition, and direct combination ... 

Sodium borohydride is the reagent of choice for the reduction of the pyridine ring in isoquinolinium salts. It reacts so rapidly that even the carbonyl group of a 1-aroyl substituent can survive (equation 154) (63JCS2487). A 1,2-dihydro intermediate has been isolated during the cyclization of (253) to 2,3-dimethoxyberbine by sodium borohydride, which suggests that a similar mechanism to that described above is operative here (equation 155) (60JOC90). 

An interesting variant uses acyl- or aroyl-methylpyridinium salts with ammonia or an amine to produce dipyridiniumdihydropyridine salts (655). With aromatic aldehydes the dihydropyridines are produced directly or the intermediate (654) can be isolated and subsequently treated with perchloric acid (75LA849). With formaldehyde (giving dihydropyridines without a substituent in position 4), the 1,5-diketone can be isolated and cyclized by ammonia (75LA864). The dipyridinium salts (655) undergo some useful transformations they can be oxidized to pyridines (656), and these dipyridinium pyridine salts give... 

Pseudo-bases derived from 2-unsubstituted 1,3-dialkylperimidinium salts disproportionate into 1,3-dialkylperimidones and l,3-dialkyl-2,3-dihydroperimidines, the former always predominate. By contrast, l-aroyl-3-alkylperimidinium salts (203), formed in situ from l-/ -perimidines and aroyl chlorides, produce pseudobases (204) which exist exclusively in the acyclic form (205). Interestingly, heating with alkali cleanly converted (205) into the corresponding 1,2-disubstituted perimidines (206). This reaction is of preparative significance for the introduction of aryl and heteroaryl groups in position 2 of perimidines (81RCR1559). 

Acyl silanes can display disparate behaviour when treated with carbon nucleophiles, even of related types5,61149. For example, when aroyl silanes were treated with a Wittig reagent, none of the expected alkenes was obtained, and the only reaction products isolated were silyl enol ether and triphenylphosphine (Scheme 73)182,183. When alkanoyl silanes were treated with Wittig reagents, however, only the normal olefinated vinyl silane products were isolated (Scheme 74)182-184 Under soluble lithium salt conditions, Z-vinyl silanes were produced with very high selectivities the reaction was used to prepare a pheromone component (50) of the sweet potato leaf folder moth (Scheme 75)183. 

Mesylates are used for Ni-catalysed reactions. Arenediazodium salts 2 are very reactive pseudohalides undergoing facile oxidative addition to Pd(0). They are more easily available than aryl iodides or triflates. Also, acyl (aroyl) halides 4 and aroyl anhydrides 5 behave as pseudohalides after decarbonylation under certain conditions. Sulfonyl chlorides 6 react with evolution of SO2. Allylic halides are reactive, but their reactions via 7t-allyl complexes are treated in Chapter 4. Based on the reactions of those pseudohalides, several benzene derivatives such as aniline, phenol, benzoic acid and benzenesulfonic acid can be used for the reaction, in addition to phenyl halides. In Scheme 3.1, reactions of benzene as a parent ring compound are summarized. Needless to say, the reactions can be extended to various aromatic compounds including heteroaromatic compounds whenever their halides and pseudohalides are available. 

Aroyl esters of anthracene-9-methanol are photolysed in methanol to give products consistent with the anthracene-9-methyl cation as an intermediate.41 Rate constants for the solvolyses of secondary alkyl tosylates in fluorinated solvents were analysed in terms of the possible involvement of very short-lived carbocation-tosylate ion pair intermediates.42 The effect of added electrolytes on the rate of solvolysis of cumyl chloride and its -methyl derivative was studied in 90% aqueous acetone and 80% aqueous DMSO, with the results revealing a combination of a special salt effect and a mass law effect.43 Kinetic parameters obtained for the solvolysis of (8) (R1 = R2 = Me and R1 = Ar, R2 = H) show that there is substantial n, n participation in the transition state [e.g. (9). 44... 

Condensation of an MSMA isonitrile with an aroylfluoride gives a salt which undergoes loss of trimethylsilyl fluoride to form a nitrile ylid. This transient species reacts with DMAD to form 2-aroyl pyrrole in high yield.162 Substitution of acyl chloride for acyl fluoride in the reaction affords only poor yields of adducts.465... 

Zugravescu et dl. (1958) considered the reaction of j8-aroyl-)3-bromoacrylic acid salts (238) with base to be an SN1 process via (239) on... 

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