Diazo acylation

Zur Umsetzung von Butadiensaure-nitril mit l-Diazo-2-oxo-propan und entsprechenden Bis-[diazo-acyl]-Verbindungen s. Bd. X/4, S. 836 (1968). 

Acid-catalyzed hydrogen exchange Halogenation Acylation and alkylation Mercuration Diazo coupling Nitrosation... 

Benzimidazole, 2-amino-5-bromo-l-methyl-diazo coupling, 5, 429 Benzimidazole, 2-amino-6-bromo-1 -methyl-diazo coupling, 5, 429 Benzimidazole, 2-amino-1-ethyl-alkylation, 5, 438 Benzimidazole, 2-amino-1-methyl-acylation, 5, 438 bromination, 5, 429 tautomerism, 5, 368 Benzimidazole, 4-amino-2-methyl-diazo coupling, 5, 429 Benzimidazole, 2-aroyl-mass spectra, 5, 360 Benzimidazole, 1-aryl-metallation, 5, 448 reactions... 

Pyrrolo[3,2-c]pyridine, 4-hydroxy-tautomerism, 4, 500 Pyrrolo[3,2-c]pyridine, 2,3,3-trimethyl-methylation, 4, 513 Pyrrolo[3,4-6]pyridine, 2-methyl-UV spectra, 4, 501 Pyrrolo[3,4-c]pyridine, 2-methyl-UV spectra, 4, 501 Pyrrolopyridines acylation, 4, 504 bromination, 4, 505 diazo coupling, 4, 506 NMR, 4, 498... 

Claisen ester condensation, 6, 279 Thiazolecarboxylic acid chlorides reactions, 6, 279-280 Thiazolecarboxylic acid hydrazides synthesis, 6, 280 Thiazolecarboxylic acids acidity, 6, 279 decarboxylation, 6, 279 reactions, S, 92 6, 274 Thiazole-2-carboxylic acids decarboxylation, S, 92 Thiazole-4-carboxylic acids stability, S, 92 Thiazole-5-carboxylic acids decarboxylation, S, 92 Thiazole-4,5-dicarboxylic acid, 2-amino-diethyl ester reduction, 6, 279 Thiazole-4,5-dicarboxylic acids diethyl ester saponification, 6, 279 Thiazolediones diazo coupling, 5, 59 Thiazoles, 6, 235-331 ab initio calculations, 6, 236 acidity, S, 49 acylation, 6, 256 alkylation, S, 58, 73 6, 253, 256 analytical uses, 6, 328 antifogging agents... 

The addition of diazo compounds generally leads to three membered tings, although in special cases, linear adducts with an intact diazo group [110] or l,3,4-oxadiazol-3-ines [111] can be isolated Most diazo compounds are unstable and yield oxirans and aziridines [112,113,114] Aziridines are obtained exclusively on reaction of certain polyfluorinated acyl imines with diazomethane [115]... 

The reactivity of the 5-position of 2-aminothiophene in diazo coupling, which is present also in the acylated derivatives, complicates the formation of a diazonium salt from 2-aminothiophene. Thus Steinkopf and Miiller obtained only an azo dyestuff, although they proved, through the isolation of small amounts of 2-thienyl diazonium chloride, the diazotizability of 2-aminothiophene which had earlier been denied. However, recent Russian work claims the preparation of 2-thienyldiazonium chloride by treating the double salt in 10% hydrochloric acid with sodium nitrite. Amazingly high yields (over 90%) of azo compounds were then achieved by coupling the diazonium salt solution with y9-naphtol, w-toluidine or with the 2-aminothiophene double salt. These authors have also studied the... 

In a first step, the carboxylic acid 1 is converted into the corresponding acyl chloride 2 by treatment with thionyl chloride or phosphorous trichloride. The acyl chloride is then treated with diazomethane to give the diazo ketone 3, which is stabilized by resonance, and hydrogen chloride ... 

To set the stage for the crucial aza-Robinson annulation, a reaction in which the nucleophilic character of the newly introduced thiolactam function is expected to play an important role, it is necessary to manipulate the methyl propionate side chain in 19. To this end, alkaline hydrolysis of the methyl ester in 19, followed by treatment of the resulting carboxylic acid with isobutyl chlorofor-mate, provides a mixed anhydride. The latter substance is a reactive acylating agent that combines smoothly with diazomethane to give diazo ketone 12 (77 % overall yield from 19). 

This preparation, specifically of acylated aryl thioglycosides, is carried out by reaction of, for instance, a 2,3,4,6-tetra-O-acety 1-1 -thio-P-D-glucopyranose with a di-azonium salt, followed by thermal decomposition of the intermediate diazo product. 

The reaction between acyl halides and diazomethane is of wide scope and is the best way to prepare diazo ketones. Diazomethane must be present in excess or the HX produced will react with the diazo ketone (10-74). This reaction is the first step of the Amdt-Eistert synthesis (18-8). Diazo ketones can also be prepared directly from a carboxylic acid and diazomethane or diazoethane in the presence of dicyclohexyl-carbodiimide. ... 

Pyrolysis of carboxylic acids Dehydrohalogenation of acyl halides Dehalogenation of a-halo acyl halides Rearrangement of diazo ketones (Wolff)... 

Carbenes from Diazo Compounds. Decomposition of diazo compounds to form carbenes is a quite general reaction that is applicable to diazomethane and other diazoalkanes, diazoalkenes, and diazo compounds with aryl and acyl substituents. The main restrictions on this method are the limitations on synthesis and limited stability of the diazo compounds. The smaller diazoalkanes are toxic and potentially explosive, and they are usually prepared immediately before use. The most general synthetic routes involve base-catalyzed decomposition of V-nitroso derivatives of amides, ureas, or sulfonamides, as illustrated by several reactions used for the preparation of diazomethane. 

Normally, the dominant reaction between acyl diazo compounds and simple ,(l-unsalurated carbonyl compounds is a cycloaddition. 

See other acyl azides, cyano compounds, diazo compounds, high-nitrogen... 

Diazaphospholes are known to undergo facile 1,3-dipolar cycloaddditions with a variety of dipoles [2, 4, 7, 98], During recent years, some interesting [2+3] cycloaddition reactions have been reported. 2-Acyl-[l,2,3]diazaphospholes 6 were reported to undergo [2+3] cycloaddition with diazocumulene 92, the minor equilibrium isomer of a-diazo-a-silyl ketones 91, to form a bicyclic cycloadduct 93 (Scheme 29). Thermolysis of the cycloadduct results in the formation of tricyclic phosphorus heterocycle 94, which can be explained due to the possibility of two parallel reactions of cycloadduct. On the one hand, extrusion of molecular nitrogen from 93... 

Kerth and Maas <1999EJ02633> have studied the reaction between (/-diazo-2-oxoalkyl)silanes and 2-acyl-l,2,3-diazaphospholes. These form the [3+2] cycloadducts 124a-l. When heated to 80-100°C, they lose molecular... 

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