XXI.—C-derivatives of hydroxytriazole

Young, George W.; Witham, Ernest

doi:10.1039/ct9007700224

Cited by 20 publications

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“…For the purpose of structure elucidation some chemical reactions on IIa and JIb were carried out. Acidic hydrolysis of IIa with alcoholic hydrochloric acid gave the known 3hydroxy-5-phenyl-1,2,4-triazole (VII) (9) and benzoic acid, while basic degradation of IIa with alcoholic sodium hydroxide produced the known 1-benzoyl semicarbazide (VIII) (10) and benzoic acid. Compound VII and VIII were formed by independent routes, because the basic conditions, whereby compound VIII was formed, could not produce a change on compound VII and furthermore, compound VIII was not cyclized to compound VII under acidic conditions similar to those whereby compound VII was produced from IIa.…”

Section: And Katsumaro Minamotomentioning

confidence: 99%

as‐Triazine chemistry. V.The oxidative ring‐opening of 5,6‐diphenyl‐as‐triazine‐3(2H)‐ones with Organic Peracids

Sasaki

Minamoto

1967

Journal of Heterocyclic Chem

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Section: And Katsumaro Minamotomentioning

confidence: 99%

as‐Triazine chemistry. V.The oxidative ring‐opening of 5,6‐diphenyl‐as‐triazine‐3(2H)‐ones with Organic Peracids

Sasaki

Minamoto

1967

Journal of Heterocyclic Chem

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“…The former examples date up to the beginning of the last century; 24 since the pioneer work by Gibson 15 their synthetic and mechanistic aspects have been systematically studied.…”

Section: Methodsmentioning

confidence: 99%

Oxidative cyclization of aldehyde thiosemicarbazones induced by potassium ferricyanide and by tris(p-bromophenyl)amino hexachloroantimoniate. A joint experimental and computational study

Meo¹,

Gruttadauria²,

Noto³

2005

Arkivoc

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The oxidative ring closure reaction of some aryl-substituted thiosemicarbazones induced by "bona fide" one-electron abstracting agents was investigated, by means of both experimental and computational techniques. The corresponding 1,2,4-triazole derivatives were the only cyclization products observed. The occurrence of two slightly different mechanistic pathways for the reaction is discussed. Keywords:Oxidative cyclization, thiosemicarbazones, 1,2,4-triazoles IntroductionThe cyclization of suitable open-chain organic molecules is a classical and very popular approach to the synthesis of heterocyclic derivatives, owing to both the large variety of heterocycles accessible through this way, and the large variety of conditions under which the reaction can be performed.1,2 Noticeably, when more than one product can be obtained at the same time in a particular reaction, good to excellent selectivities can often be achieved (and sometimes reverted) by means of a suitable choice of the cyclizing agent and conditions. [2][3][4][5] Frequently, such cyclization reactions are induced by acidic media or electrophilic reagents. In the latter case, this might involve de facto a formal oxidation of the organic substrate, as an implicit consequence of the process (the cyclo-etherification or lactonization of unsaturated alcohols and acids induced by halogens or sulfinyl and selanyl halides provides a typical case). 3,[5][6][7][8][9][10][11][12][13] In other occasions, the cyclization mechanism involves a plain oxidation stepelectron abstraction or dehydrogenation -prior to the actual ring closure step. Examples of these reactions have been recently reviewed. Aldehyde semicarbazones and thiosemicarbazones 1 are typical substrates which may undergo ring closure processes induced by an oxidizing agent, to afford the corresponding 1,2,4-triazole 2 and 1,3,4-oxa-or -thiadiazole 3 derivatives (Scheme 1). There is now enough evidence that the reaction may follow very different courses, depending on the substrate structure (in particular on the alkyl or aryl substituent groups placed on its main molecular framework) and on the oxidizing agent used. In particular, we have been interested in the oxidation of aryl-substituted thiosemicarbazones induced by high-valent (Fe) metal salts. [19][20][21][22][23] Despite the apparent similarity of these reagents, surprisingly we observed that very different results -both in terms of reaction regiochemistry and yields, and in terms of reaction kinetics -can be achieved by the use of different salts, depending on the hardness/softness of the metal cation (or, more properly, of the solvated metal-counteranion complex), as well as on its intrinsic oxidizing strength. On the grounds of a careful analysis of all available data, we proposed 2a,22,23 (Scheme 2) that the formation of the 1,2,4-triazole ring could be induced by an attack of the oxidizing agent on the tail thioamide-like moiety of the molecule, followed by a single electron transfer (s.e.t.) step and then by a rate-limiting ring clo...

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“…separate the simpler aliphatic aldehydes from ketones.1 Subsequently, it was found that the reactivity of the carbonyl group in such compounds stands in a direct relation to the affinity constant of the acid combined with phenylhydrazine, but that for qualitative and quantitative determinations semicarbazide2 as base is better adapted for the purpose. 8 In recent years the reaction velocities of ketones and aldehydes with various reagents have been investigated quantitatively by Petrenko-Kritschenko and collaborators, as well as by Stewart, and the results have been used as a basis for theoretical conclusions,4 which will be discussed in a later paper. It is evident that the relative reaction velocities of such compounds with reagents should be used for theoretical speculations, and for conclusions regarding the relations to their chemical structures, only when the cause of the velocity and the difference between it and reactivity have been satisfactorily analyzed and explained.…”

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“…Stability is the result of a more or less complete neutralization of the atomic forces 1 According to an unpublished investigation with Mr. G. H. Shadinger, ketones of the types CH3-CO-C»H2»-fi, C2H5-CO-• .2 + , excepting ethylamyl ketone, and CsH?-CO-C*H2H + i give phenylhydrazones even in the presence of o.2 N free hydrochloric acid; some of these hydrazones, for instance, those of methylethyl-, methylpropyl-, methylbutyl-and diethyl-ketones pass over in the cold, in presence of an excess of hydrochloric acid, into the corresponding indole chlorohydrates. 8 Thiele and Stange, Ber., 29, 31 (1894); Ann., 283, 1 (1894). 8 Michael, J. prakt.…”

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The Relations Between the Chemical Structures of Carbonyl Derivatives and Their Reactivities Toward Salts of Semicarbazide.

Michael¹

1919

J. Am. Chem. Soc.

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I When prepared under carefully controlled conditions protein-free milk is variable in composition.2 . A&Q nitrogen determinations before and after acid hydrolysis and the nitrogen distribution indicate that either unprecipitated protein or peptids of considerable size are present in protein-free milk.3. By precipitation with acid mercuric nitrate or phosphotungstic acid a little less than of the nitrogenous compounds is removed. Fxainination of the phosphotungstic acid precipitate indicates that this reagent removes only nona-amino nitrogen.4. Furthev proof that conjugated amino groups are present in proteinfree inilk is shown by the increase in amino nitrogen after tryptic digestion. ST PAUL, MINNESOTA. [CGWTRrBlJTIQN FROM TEE DlVISIGN QF CH@MIS'I'RY, MARVARD UNIVERSITY. ] I LATHONS BETWEEN TEE CHEMICAL ST IVATIVES AND THEIR REACTIVITIE ~E~~C~R~A~~~E . BY ARTKUX MICKAEL.

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XXI.—C-derivatives of hydroxytriazole

Cited by 20 publications

References 0 publications

as‐Triazine chemistry. V.The oxidative ring‐opening of 5,6‐diphenyl‐as‐triazine‐3(2H)‐ones with Organic Peracids

as‐Triazine chemistry. V.The oxidative ring‐opening of 5,6‐diphenyl‐as‐triazine‐3(2H)‐ones with Organic Peracids

Oxidative cyclization of aldehyde thiosemicarbazones induced by potassium ferricyanide and by tris(p-bromophenyl)amino hexachloroantimoniate. A joint experimental and computational study

The Relations Between the Chemical Structures of Carbonyl Derivatives and Their Reactivities Toward Salts of Semicarbazide.

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