Ethanols, aryl-substituted—

Aryl-substituted biguanides (c.g. 1) can be condensed with 1-benzoylacetone to provide 1,3,5-triazocine derivatives,13 Two isomers of product 2 can be isolated upon recrystallization from ethanol. The isomers, probably tautomers 2A and 2B, exhibit the same melting point and rapidly interconvert in solution, thereby giving identical NMR spectra in deuteriochloroform at room temperature. 

Benzotriazine, and especially its conjugate acid, reacts very easily with nucleophiles such as water or acetic acid to give derivatives of 2-aminobenzaldehyde (75JCS(P1)31,71CC828). 4-Alkyl- or 4-aryl-substituted 1,2,3-benzotriazines are more stable towards attack of water or acids. 2-Aminobenzophenone (100%) is obtained when 4-phenyl-1,2,3-benzotriazine is heated under reflux for 10 min in 10% aqueous ethanol containing concentrated sulfuric acid (75JCS(Pl)3l>. 

The complexes with unsubstituted and either alkyl- or aryl-substituted glyoximes have been prepared by the reaction of nickel(II) salts with the appropriate ligand in aqueous or ethanolic solution or an aqueous-ethanolic mixture. In most cases, the reaction is promoted by addition of ammonia as base and/or refluxing temperature. 

Hexaphyrin(l.1.1.1.0.0) 163 (Scheme 67) represents an isomer of ruby-rin, which was prepared (00JCS(CC)1473) in 46% yield by acid-catalyzed condensation of an equimolar mixture of meso-aryl-substituted tripyr-rane 155 with the diformylhexamethylterpyrrole 162 in ethanol in the... 

The treatment of a variety of 2-aryl substituted isothiazolo[5,4-6]pyridin-3-ones (210) with sodium hydroxide in refluxing ethanol for 15 min cleaved the isothiazole ring and gave the pyridines (211) in yields ranging from 60-70% <88JHC23>. 

The skeletal structure of 3-hydroxy-l,2,5-thiadiazole was determined through reductive desulfurization with Raney nickel in ethanol which formed A, A-diethylaminoacetamide, Eq. (6). The same product was obtained by subjecting the proposed intermediate, glycinamide, to the same reaction conditions. The aryl-substituted thiadiazoles (64) were reduced to a-diamines with sodium and alcohol. 

Aryl-substituted cyclopropyl ketones, e.g. 34, are reductively cleaved to acyclic ketones by refluxing in ethanol, or butanol, with zinc metal or a mixture of zinc metal and zinc(II) chloride. The reaction is thought to proceed via radical anion intermediates analogous to those of the lithium/ammonia process. Various substituted derivatives were studied and the aryl substituent in the cyclopropane ring was found to be essential alkyl-substituted analogs were not reductively cleaved with this reagent. 

Condensation of the 1,3-dione (219) with thiosemicarbazide in refluxing ethanol gave (115), this being one of the few synthetic routes which provides aryl substituted analogues <92BCJ3419>. Thione (221) was obtained when (220) was allowed to react with benzoyl isothiocyanate <93JCR(S)352>. Amidrazone (222) condenses with 1,3-dicarbonyl compounds to yield (223) by addition, oxidation, and condensation <94JHCI157>. 

The enantioselective protonation of silyl enol ethers, such as (12.39), by a catalyst has been achieved using 2 mol% of the proton source (12.40). The acidity of (12.40) is enhanced by coordination to a Lewis acid. The silyloxy group is activated by fluoride ion and up to 99% ee in the asymmetric protonation of a-aryl substituted cyclic silyl enol ethers such as (12.39) has been obtained using a Lewis acidic BINAP. / F complex.In a similar vein, silyl enol ethers of tetralones and indanones undergo asymmetric protonation with moderate to good ee using catalytic quantities of hydrogen fluoride salts of cinchona alkaloids in the presence of acyl fluorides and ethanol, which act as a stoichiometric source of HE 28... 

The use of special enamines in the three-component Knoevenagel-Michael addition/cyclization sequence directly led to Af-alkyl- or Af-aryl-substituted 2-amino-4//-pyrans. Perumal et al. therefore applied catalytic amounts of piperidine in ethanol at ambient temperature to add ( )-Al-methyl-l-(methylthio)-2-nitroethenamine 49 to the previously formed Michael acceptor in a one-pot fashion (Scheme 13.16) [7]. This protocol provides the desired lV-methyl-2-amino-4//-pyrans 50/51 in good yields. The methylthio substituent serves as a good leaving group facilitating the cyclization subsequent to the Michael addition reaction by nucleophilic substitution. 

Group of reactions the transformation of a functional group within a substructure (e.g., homologation of aryl substituted methanols to aryl substituted ethanols)... 

The usefulness of the Gewald reaction for the synthesis of 2-amino-3-carbonyl-substituted thiophens has been amply demonstrated during the past two years (c/. ref. 6fl). These thiophens are very useful starting materials for complex condensed systems of pharmacological interest. I.r. and n.m.r. studies showed some anomalies which were interpreted in terms of electron delocalization in the enaminocarbonyl structure. From cyanoacetamide, benzylacetone, and sulphur, the thiophen (9) was obtained. 3-Aryl-substituted derivatives such as (10) were obtained from the appropriate aryl methyl ketone, ethyl cyanoacetate, and sulphur. It has been claimed that (11) is obtained from the reaction of acetoacetic acid anilide with malononitrile and sulphur. This hardly seems to be correct, as (12) is the product expected in the Gewald reaction. It was found that 2-amino-3-ethoxycarbonyl-thiophens (13) react with sodium ethoxide in ethanol, pre-... 

The reactant corresponding to retrosynthetic path b in Scheme 2.2 can be obtained by Meerwein arylation of vinyl acetate with o-nitrophcnyldiazonium ions[9], Retrosynthetic path c involves oxidation of a 2-(o-nitrophenyl)ethanol. This transformation has also been realized for 2-(o-aminophenyl)ethanols. For the latter reaction the best catalyst is Ru(PPhj)2Cl2. The reaction proceeds with evolution of hydrogen and has been shown to be applicable to a variety of ring-substituted 2-(o-aminophenyl)ethanols[10]. 

In 1883, Bottinger described the reaction of aniline and pyruvic acid to yield a methylquinolinecarboxylic acid. He found that the compound decarboxylated and resulted in a methylquinoline, but made no effort to determine the position of either the carboxylic acid or methyl group. Four years later, Doebner established the first product as 2-methylquinoline-4-carboxylic acid (8) and the second product as 2- methylquinoline (9). Under the reaction conditions (refluxing ethanol), pyruvic acid partially decarboxylates to provide the required acetaldehyde in situ. By adding other aldehydes at the beginning of the reaction, Doebner found he was able to synthesize a variety of 2-substituted quinolines. While the Doebner reaction is most commonly associated with the preparation of 2-aryl quinolines, in this primary communication Doebner reported the successful use of several alkyl aldehydes in the quinoline synthesis. 

Reactivity in this ring system is sufficient for facile hydrolysis (20°, 2 hr or 100°, 1 min) of the 2-, 4-, 6-, and 7-methoxypteridines in high yield and for easy substitution (75-90% yields) of the 7-methylthio group with methanolic hydrazine hydrate (65°, 15 min), dimethylamine (65°, 30 min), and ethanolic ammonia (125°, 6 hr). The 7-acyloxy intermediate in thionation of 7-oxopteridine with phosphorus pentasulfide is readily substituted (80°) to form pteridine-7-thione. The chloro group in 6-aryl-2,4-diamino-7-chloro-pteridine still reacts readily with hydrazine (100°, several minutes) in spite of the two deactivating amino substituents. 

Bromoquinolines behave in the Suzuki reaction similarly to simple carbocyclic aryl bromides and the reaction is straightforward. Examples include 3-(3-pyridyl)quinoline (72) from 3-bromoquinoline (70) and 3-pyridylboronic acid (71) (91JOC6787) and 3-phenyl-quinoline 75 from substituted 3,7-dibromoquinoline 73 and (2-pivaloylaminophenyl)boronic acid 74 (95SC4011). Notice that the combination of potassium carbonate and ethanol resulted in debromination at the C(7) position (but the... 

Scheme 11.6 gives some examples of the various substitution reactions of aryl diazonium ions. Entries 1 to 6 are examples of reductive dediazonization. Entry 1 is an older procedure that uses hydrogen abstraction from ethanol for reduction. Entry 2 involves reduction by hypophosphorous acid. Entry 3 illustrates use of copper catalysis in conjunction with hypophosphorous acid. Entries 4 and 5 are DMF-mediated reductions, with ferrous catalysis in the latter case. Entry 6 involves reduction by NaBH4. 

Condensation of aromatic acyl compounds with N,N-dimethylformamide diethyl acetal in a pressure tube under the action of microwave irradiation affords easy access to l-aryl-3-dimethylaminoprop-2-enones in almost quantitative yield after 6 min. These intermediates can then be reacted with hydrazine hydrate under conventional reflux in ethanol to form the corresponding 3-substituted pyrazoles [95] (Scheme 8.69). 

The reaction of the stable and readily available N-protected (a-aminoacyl)benzotriazoles 215 (Equation 36) with amidoximes 206 in ethanol gave the N-protected 5-amino-substituted 1,2,4-oxadiazoles 216 in high yield, under mild conditions and with good (>97%) retention of chirality <2005ARK36>. The method is also applicable to aromatic (V-acylbenzotriazoles, giving access to 5-aryl-l,2,4-oxadiazoles in 73-82% yield. 

The kinetic studies on the solvolysis of 1 -aryl-l-chloro-3-methylbuta- 1,2-dienes (15, Ar = Ph, p-MeOCgH4) showed that the p values (p+ = —2.8 in 80% aqueous ethanol and —2.9 in aqueous acetone)21 are much lower than those of the correspondingly substituted vinyl derivative 16 (p+ = —4.3 in aqueous ethanol)22. This result indicates that the u-substituent effect in cations 17a is much smaller than in the vinyl cations, suggesting... 

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