Transfers diazo groups

Quinone diazides can also be obtained by the diazo group transfer reaction of 4-tosyl azide. For example, 9-diazo-10-anthrone (2.55) is formed from anthrone (2.54) if the reaction is carried out in an ethanol-piperidine mixture. On the other hand, if ethanol is replaced by pyridine, dimerization with loss of molecular nitrogen takes place and the azine 2.56 is isolated (Scheme 2-32 Regitz, 1964 Cauquis et al., 1965). In the preceding discussion tosyl azide was shown to be an electrophilic reagent. It therefore seems likely that it is not the anthrone 2.54 but its conjugate base which reacts with tosyl azide. 

Detrifluoroacetylative Diazo Group Transfer (E)-1 -Diazo-4-phenyl-3-buten-2-one. 

A reaction known as diazo group transfer produces diazo barbituric acid from barbituric acid and p-toluene sulfonyl azide. Additional barbituric acid affords azo barbituric acid [7]. Subsequent complexation with a nickel (II) salt yields a greenish yellow pigment. 

Bis-acceptor-substituted diazomethanes are most conveniently prepared by diazo group transfer to CH acidic compounds either with sulfonyl azides under basic conditions [949,950] or with l-alkyl-2-azidopyridinium salts [951] under neutral or acidic conditions [952-954]. Diazo group transfer with both types of reagents usually proceeds in high yield with malonic acid derivatives, 3-keto esters and amides, 1,3-diketones, or p, y-unsaturated carbonyl compounds [955,956]. Cyano-, sulfonyl, or nitrodiazomethanes, which can be unstable or sensitive to bases, can often only be prepared with 2-azidopyridinium salts, which accomplish diazo group transfer under neutral or slightly acidic reaction conditions. Other problematic substrates include amides of the type Z-CHj-CONHR and P-imino esters or the tautomeric 3-amino-2-propenoic esters, which upon diazo group transfer cyclize to 1,2,3-triazoles [957-959]. 

The starting diazoacetamide is prepared by N-arylation of /-phenylalanine methyl ester (DMP, 5.5 M 4-fluoronitrobenzene, 110°C, lOh, 30%), acetoa-cetylation (2,2,6-triraethyl-4/7-l,3-dioxin-4-one, toluene, 110 °C, 4h, 71%) and diazo group transfer (tosyl azide, triethylamine, acetonitrile, 20 °C, 1.5 h, 90%). 

The syntheses shown in Scheme 26 (71CB1573) are based on dibenzo-/3-tropolone (108) and its enamines. Condensation of 108 and benzoin in the presence of ammonia affords pyrrole 109. The morpholino enamine gives pyrazole 110 via benzoylation, hydrolytic elimination of morpholine, and cyclization, whereas diazo-group transfer onto the anilino enamine leads to triazole 111. Dione 108 and p-nitrophenylazide in one step give predominantly the p-nitro derivative of 111 (92G249). 

Trimethylsilyldiazomethane, as a stable and safe substitute for hazardous diazomethane, is useful both as a reagent for introducing a Cj-unit and as a C-N-N synthon for the preparation of azoles. Many methods are described in the literature for the preparation of trimethylsilyldiazomethane, including the trimethylsilylation of diazomethane (7-74S), the alkaline decomposition of N-nitroso-N-(trimethylsilylmethyl)amides (25-61%) and the diazo group transfer reaction of trimethylsilylmethyllithium with p-toluenesulfonyl azide (38%). The present modified diazo group transfer method appears to be the most practical, high-yield, and large scale procedure for the preparation of... 

In addition to previously described syntheses4-5 by diazo group transfer with deformylation,6 2-diazocyclohexanone has been prepared by two variants of this method. In one, the reaction of 2-(hydroxymethylene)cyclohexanone with -toluene-sulfonyl azide is carried out in ether/diethylamine, and an enamine is assumed to be formed as an intermediate 7 in the other, the sodium salt of the hydroxymethylene compound was treated with the lithium salt of p-carboxybenzenesulfonyl azide... 

Numerous methods to prepare individual classes of aliphatic diazo compounds have been extensively developed. The major strategies for their synthesis involve the alkaline cleavage of N-alkyl-N-nitroso-ureas, -carboxamides and -sulfonamides, dehydrogenation of hydrazones, as well as diazo group transfer from sulfonyl and related azides to active methylene compounds, and electrophilic diazoalkane substitution reactions. These synthetic methods have been comprehensively reviewed (15,16). Useful information on the preparation of selected diazo compounds can be found elsewhere (6,17). 

Diazoamides of type 300 rapidly cyclize to form aziridines 302 (342) (Scheme 8.73). It is conceivable that this reaction proceeds through a 1,2,3-triazoline intermediate 301, which is the consequence of a LUMO(dipole)— HOMO(dipolarophile) controlled intramolecular [3 + 2] cycloaddition. Some remarkable steric effects were encountered for this cyclization. While the piperidine derivative [300, = ( 112)4] readily cyclized by diazo group transfer at... 

Lastly, a-diazotization of ketophosphonium salts with azidinium tetrafluoroborate as a diazo group transfer agent has been described as a general process840 (reaction 258). 

A diazo group transfer from the benzthiazolium azide 97 to 2,6-diamino-pyridine gives the 5-aminotriazolopyridine 98.187... 

Furo[3,4-d]oxazoles (e.g., 86 colorless crystals with mp 143°C) are available from 85 by diazo group transfer and subsequent extrusion of nitrogen (97UP4 98JOC7680). 

Diazocarbonyl compounds can be prepared on insoluble supports by diazo group transfer with sulfonyl azides or by diazotization of primary amines. Diazo group transfer from sulfonyl azides to 1,3-dicarbonyl compounds proceeds on cross-linked polystyrene as smoothly as in solution (Table 10.19). When 3-keto esters or amides are... 

Fig. 14.29. Preparation of an a-diazoketone (compound E) from a ketone (A) and subsequent Wolff rearrangement of the a-diazoketone. Initially, A is transformed to give the enolate B of its a-formyl derivative. In a Regitz diazo group transfer reaction, this will then be converted into the a-diazoketone E. Ring contraction via Wolff rearrangement occurs and the 10-membered cyclic diazoketone C rearranges in aqueous media to give the nine-membered ring carboxylic acid E via the ketene D.

Fig. 15.42. Preparation of diazomalonic ester via diazo group transfer via the Regitz procedure.

Diazomalonic ester is another important 1,3-dipole for synthesis. We saw the kinetics of 1,3-dipolar cycloadditions of diazomalonic ester earlier, in the discussion of Figure 12.36. The preparation of this 1,3-dipole is accomplished most conveniently with the procedure shown in Figure 12.39 diazo group transfer according to Regitz. 

DETRIFLUOROACETYLATIVE DIAZO GROUP TRANSFER (E)-1-DIAZO-4-PHENYL-3-BUTEN-2-ONE (3-Buten-2-one, 1-diazo-4-phenyl-)... 

The importance of a-diazo ketones as synthetic intermediates has led to the development of a number of general methods for their preparation.5 Particularly popular approaches include the acylation of diazo alkanes and the base-catalyzed "diazo group transfer" reaction of sulfonyl azides with 8-dicarbonyl compounds.6-7 While direct diazo transfer to ketone enolates is usually not a feasible process,8-9 diazo transfer to simple ketones can be achieved in two steps by employing an indirect deformylative diazo transfer strategy in which the ketone is first formylated under Claisen condensation conditions, and then treated with a sulfonyl azide reagent such as p-toluenesulfonyl azide.6a,6c,9,i0,11... 

Cyclopentadimylidene (2). 2 was very easily obtained by photolysis or thermolysis of the corresponding diazo-cyclopentadienes (72). These were prepared by straightforward procedures (diazo-group transfer, dehydrogenation of hydrazones, or Bamford-Stevens reaction of tosyl-hydrazones) 26-80) from either cyclopentadienes (77) or substituted cyclopentadienones (73). 

Carbena-cyclohexadienone (3). Photolysis or thermolysis of -quinone diazides (15) easily led to 3. The precursors of 3 are either />-aminophenols (14), -quinones (77) or anthrones (76). Diazotization of 14, Bamford-Stevens reaction of the tosyl-hydrazone of 77, or diazo-group transfer to 76 afforded the corresponding -quinonediazides 15 31-84)... 

Diazogroup transfer. Rcgit ha.s reviewed diazo group transfer to active methylene... 

Regitz, M. Reactions of carbon-hydrogen active compounds with azides. XIII. Diazo group transfer. Neuere Method. Praep. Org. Chem. 

Regitz, M., Rueter, J. Reactions of CH-active compounds with azides. XVIII. Synthesis of 2-oxo-1-diazo cycloalkanes by deformylative diazo-group transfer. Chem. Ber. 1968, 101, 1263-1270. 

Danheiser, R. L., Miller, R. F., Brisbois, R. G. Detrifluoroacetylative diazo group transfer (E)-1-diazo-4-phenyl-3-butene-2-one (3-buten-2-one, 1-diazo-4-phenyl-). Org. Synth. 1996, 73, 134-143. 

Regitz, M., Menz, F., Lledhegener, A. Reactions of CH-actIve compounds with azides. XXVIII. Synthesis of a, 3-unsaturated dIazoketones by deformylating diazo group transfer. Liebigs Ann. Chem. 1970, 739, 174-184. 

---