Bis-diazoketone

The distinction between Pd and Rh catalysts was also verified for diazoketone 190. In this case, the carbonyl ylide was trapped by intramolecular [3+2] cycloaddition to the C=C bond195. Decomposition of bis-diazoketone 191 in the presence of CuCl P(OEt)3 or Rh2(OAc)4 led to the pentacyclic ketone 192 most remarkably, one diazoketone unit reacted by cyclopropanation, the second one by carbonyl ylide formation 194). With [(r 3-C3H5)PdCl]2, a non-separable mixture containing mostly polymers was obtained, although bis-diazoketones with one or two allyl side chains instead of the butenyl groups underwent successful twofold cyclopropanation 196). 

Heating the bis-diazoketone 144 generates the pyrazol-4-one 145, which was trapped as the bicyclic adduct 146 in the presence of 2,3-dimethylbuta-l,3-diene (equation 79)69. 

Silirenes (140, equation 32) could also be involved in the transition-metal catalyzed decomposition of bis(diazoketones) 139 which provides the electron-rich [4]radialenes 14266,67. While the formation of 142 directly from silirene 140 cannot be excluded a priori, it is more reasonable to assume that 140 undergoes twofold ring-expansion to form the cyclic cumulene 141, which then provides 142 by a cyclodimerization reaction. The intermediacy of 141 is corroborated by the isolation of the Diels-Alder product 14366. 

Dodecanedioic acid. Add, with stirring, a solution of 5 g (0.02 mol) of the bis-diazoketone in 100 ml of warm dioxane to a suspension of 6.0 g of freshly precipitated silver oxide (2) in 250 ml of water containing 8 g of sodium thiosulphate maintained at 75 °C. A brisk evolution of nitrogen occurs after 1.5 hours at 75 °C, filter the liquid from the black silver residue. Acidify the almost colourless filtrate with nitric acid and extract the gelatinous precipitate with ether. Evaporate the dried ethereal extract the residue of crude dodecanedioic acid weighs 3.3 g (72%), and has m.p. 116-117 °C. Recrystallisation from 20 per cent aqueous acetic acid raises the m.p. to 127-128 °C. 

Alternatively, treat 3.9 g (0.0156 mol) of the bis-diazoketone in 50 ml of warm dioxane with 15 ml of 20 per cent aqueous ammonia and 3 ml of a 10 per cent aqueous silver nitrate solution under reflux in a 250- or 500-ml flask on a water bath. Nitrogen is evolved for a few minutes, followed by a violent reaction and the production of a dark brown opaque mixture. Continue heating for 30 minutes on the water bath and filter hot the diamide of dodecanedioic acid is deposited on cooling. Filter the product and air dry the yield is 3.1 g (87%), m.p. 182-184 °C, raised to 184-185 °C after recrystallisation from 20 per cent aqueous acetic acid. Hydrolyse the diamide by refluxing for 2-5 hours with a four molar excess of 3m potassium hydroxide solution. Acidify and recrystallise the precipitated acid from 20 per cent acetic acid. The yield of dodecanedioic acid, m.p. 127-128 °C, is almost quantitative. 

Oxidation has been used to convert one type of dimeric skeleton to another. Thus, a mixture (421) of racemic berbamunine and magnoline, prepared via the bis diazoketone 422, was oxidized with buffered K3Fe(CN)6 to 423, which was methylated to a mixture of pakistanamine (46) isomers (283). Electroreduction... 

The quantum yield of nitrogen formation obtained from the photolysis of various diazoketones in methanol has been measured as a function of the nature of the substituent (Table 13) . In general, decreases with increasing polarization of the diazo group p- and w-substituents decrease (j) when R = phenyl. For bis-diazoketones 0 (per N2) is unaffected unless there is strong conjugation. The quantum yields are also lowered in polar media and correlations with the Hammett equation indicates that the excited state is triplet . 

The bis(diazoketone) (N.CHCOC-H,), derived from diphenic acid, forms the... 

It is possible to use bis(diazoketones) for the synthesis of bisketenes as well as for Arndt-Eistert reactions. Such cases were studied by Gleiter et al. (1992) and by the group of Prinzbach in the context of dodecahedrane and related syntheses (e.g., Fessner et al., 1983 Melder et al., 1992). 

Tri-O-acetylxylaryl dichloride reacted with diazomethane to give the expected bis(diazoketone) and a by-product having structure (146), which yielded the heptopyranulose derivative (147) on treatment with hydrogen bromide. A mixture of the 2,7-anhydro derivatives (148) and (149) was obtained when (147) reacted with sodium azide in acetone. 

The bis(diazoketone) (483) prepared from 2,3,4-tri-O-acetylxylaryl dichloride cyclized to give the branched-chain cyclitol (484) on heating in acetic acid containing copper(ii) acetate. Reduction of (484) and acetylation of the products gave the DL-2-C-hydroxymethyl-epi-inositol hexa-acetate (485). 

Rhodium(II) acetate was found to be much more superior to copper catalysts in catalyzing reactions between thiophenes and diazoesters or diazoketones 246 K The outcome of the reaction depends on the particular diazo compound 246> With /-butyl diazoacetate, high-yield cydopropanation takes place, yielding 6-eco-substituted thiabicyclohexene 262. Dimethyl or diethyl diazomalonate, upon Rh2(OAc)4-catalysis at room temperature, furnish stable thiophenium bis(alkoxycarbonyl)methanides 263, but exclusively the corresponding carbene dimer upon heating. In contrast, only 2-thienylmalonate (36 %) and carbene dimer were obtained upon heating the reactants for 8 days in the presence of Cul P(OEt)3. The Rh(II)-promoted ylide formation... 

The Cu semicorrin complex (68a) has been successfully used as the catalyst for cyclization of alkenyl diazoketones, though the reactions of some substrates showed modest enantioselectivity (Scheme 74).276 Shibasaki et al. have successfully used the cyclization of diazoketone with Cu bis(oxazoline) (101) for the construction of the CD ring skeleton of phorbol.277... 

The 3//-l,2,4-diazaphospholes formed from the reaction of diazomethane and its monosubstituted derivatives (R CH=N2 R = H, alkyl, aryl, acyl, phosphoryl) could not be isolated due to a rapid 1,5-H shift leading to 27/-l,2,4-diazaphospholes 227. When diazo(trimethylsilyl)methane or [bis(diisopropylamino)phosphino]dia-zomethane was used, the l,5-SiMe3 [or PR2, R = N(/-Pr)2] shift completely dominates over the H shift (289,290). In the case of open-chain or cyclic a-diazoketones, cycloadducts 228 cannot be isolated due to rapid acyl shifts giving 229 and ultimately 230 (289). This transformation offers a versatile method to prepare [h]-fused 1,2,4-diazaphospholes from cyclic a-diazoketones and phos-phaalkynes (289). 

Diazomethane attacks the thione group of the 3,l-benzothiazine-4-thione (32) to give the bis-(l,3-dithiolane) (33), whereas diazoketones afford 4-methylene derivatives (34) (71BSF187). 

Carbenoid transformations involving competition between intramolecular cyclopropa-nation and /8-hydride elimination have been investigated149. The chemoselectivity of these catalytic transformations can be effectively controlled by the choice of catalyst. Rhodium(II) trifluoroacetate catalysed decomposition of diazoketone 111 proceeds cleanly to give only enone 112. However, rhodium(II) acetate or bis-(iV-t-butylsalicyladiminato) copper(II) cu(TBs)2 provides exclusively cyclopropanation product 113 (equation 102)149. 

Diacidic phosphonates (Vla-VId), i.e., those with two protons available for substitution, had a tendency to yield significant a-mounts of bis-substituted phosphonates [(RiC0CH20)2P0(R2) ] upon reaction with IV. However, it was found that careful addition (Table I) of the a-diazoketone to the phosphonate at reaction temperature minimized the formation of this by-product moreover, the bis-substituted phosphonates could be converted to the corresponding monoacids by refluxing the former with sodium iodide in methyl ethyl ketone. In this manner higher yields of phosphonates (e.g., Vllla-VIIId) could be obtained. 

The synthesis and relative stability of 3,5-diacyl-4,5-dihydro-l//-pyrazoles prepared by dipolar cycloaddition of enones and a-diazoketones has been published <2004JOC9085>. 3-Acyl-4-aryl-2-pyrazolines have been synthesized by the reaction of a,/3-unsaturated ketones with diazomethane <1996IJB1091>. Ethyl diazoacetate added to 1,3-diarylpropenones in a regioselective fashion to give the intermediate 4,5-dihydto-3//-pyrazole derivative 1,3-hydride shift in the latter led to the formation of the isomeric ethyl 4-aryl-5-aroyl-4,5-dihydro-l//-pyrazole-3-carboxylate and ethyl 4-aryl-3-aroyl-4,5-dihydro-l/7-pyrazole-5-carboxylate in a ratio of 5 1 <2001RJ01517>. 1,3-Dipolar cycloaddition of 2-diazopropane with diarylideneacetones afforded diastereomeric bis-A -pyrazolines <1999T449>. 

Cyclization of /3-mercaptoaldehydes has been reported to give 2-hydroxy-thietanes (which are thioacetals) in 16-84% yield.They are said to be useful as flavoring substances. However, cyclization of 4-mercaptopropene gave only 0.1% of 2-methylthietane. The major product was thiolane. Photolysis of the a-diazoketone of 2,2,5,5-tetramethylthiolane-3,4-dione in methanol gave a 28% yield of 2,2,4,4-tetramethyl-3-carbomethoxythietane. " Several dispirothietanes have been obtained from the bis-hydrazone of 3-thietanone. ... 

The unstable bis-3-methylenethietane 392 is obtained by desulfurization of the thiirane 391 that is derived from 384, The thermal rearrangement of a-diazoketone 362 gives the 2-methylene-3-thietanone 363 in quantitative yield. 

Intramolecular cyclization of bis-a-diazoketones. The decomposition of 1,7-bisdiazoheptane-2,6-dione (1) with this copper chelate in boiling benzene under high dilution conditions affords cyc ohept-2-ene-l,4-dione (2) in 32% yield.1 A lower yield (20%) is obtained if copper bronze is used as catalyst. 

The intramolecular cyclopropanation of several unsaturated diazo carbonyl compounds83 is most efficiently catalyzed by the Aratani complex (A)-4. Thus, 1-diazo-5-hexen-2-one is converted into (15",5i )-2-oxobicyclo[3.1.0]hexane with 77% ee, An interesting aspect of this study is the activation of the catalyst by bis(2-methylpropyl)aluminum hydride, which reduces the copper(II) to give a copper complex. Other unsaturated diazoketones with the / -complex 4 gave inferior results and with a-diazo /i-oxo esters, which require higher temperatures for carbenoid formation, the enantiomeric excesses were close to zero. 

A number of modified steroids are known in which one of the rings is contracted by one carbon atom relative to the normal tetracyclic steroid nucleus via diazotization. Irradiation of diazoketones affords D-nor-, A-nor, and A-bis-nor-androstane carboxylic acids (22 9-231).20,46... 

Diazoketone sowie 1, [Pg.735]

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