O- diazoacetophenon

An alternative approach in the asymmetric catalysis in 1,3-dipole cycloaddition has been developed by Suga and coworkers. The achiral 1,3-dipole 106 was generated by intramolecular reaction of an Rh(ii) carbene complex with an ester carbonyl oxygen in the Rh2(OAc)4-catalyzed diazo decomposition of <9-methoxycarbonyl-o -diazoacetophenone 105 (Scheme 12). The asymmetric induction in the subsequent cycloaddition to G=G and G=N bond was achieved by chiral Lewis acid Sc(iii)-Pybox-/-Pr or Yb(iii)-Pybox-Ph, which can activate the dipolarophile through complexation. With this approach, up to 95% ee for G=0 bond addition and 96% ee for G=G bond addition have been obtained, respectively. ... 

Fierz-David and Ziegler (301) first applied this method to azo compounds. Ethyl acetoacetate and various aromatic amines (aniline, o- and p-toluidines, m-xylidine, o-anisidine, and chloroanilines) were convereted to acetoacetanilides and then coupled with diazotized sulfanilic acid. The azo dyes (38) were reduced with stannous chloride in hydrochloric acid to the corresponding aminoaceto-acetanilides (39), which in alkali formed the dihydropyrazines (40). Catalytic reduction of o-hydroxyphenylglyoxal phenylhydrazone in acetic acid over palladium has been shown also to give 2,5-bis(o-hydroxyphenyl)pyrazine (302). Reduction of chemical means has been shown to give... 

Interaction of a carbonyl group with an electrophilic metal carbene would be expected to lead to a carbonyl ylide. In fact, such compounds have been isolated in recent years the strategy comprises intramolecular generation of a carbonyl ylide whose substituent pattern guarantees efficient stabilization of the dipolar electronic structure. The highly reactive 1,3-dipolar species are usually characterized by [3 -I- 2] cycloaddition to alkynes and activated alkenes. Furthermore, cycloaddition to ketones and aldehydes has been reported for l-methoxy-2-benzopyrylium-4-olate 286, which was generated by Cu(acac)2-catalyzed decomposition of o-methoxycarbonyl-o-diazoacetophenone 285... 

A soln. of o)-diazoacetophenone in tetrahydrofuran added gradually at 0° to a stirred soln. of triethylborane in anhydrous tetrahydrofuran, stirred 1.5 hrs. at room temp, until Ng-evolution is complete, a soln. of the Mannidi reagent di-methyl(methylene)ammonium iodide in anhydrous dimethyl sulfoxide added with stirring, which is continued at room temp, up to 3 hrs., cooled to 0°, 3 iV NaOH-soln. added, and vigorously stirred for 15 min. l-phenyl-2-dimethylamino-methyl-l-butanone. Y 70-92%. F. e. s. J. Hooz and J. N. Bridson, Am. Soc. 95, 602 (1973). 

Ludwig Wolff made the discovery that diazo ketones can be converted into derivatives of an acid in 1915. Wolff found, for example, that the treatment of (o-diazoacetophenone (PhCOCHN2) with ethanolic ammonia and a silver... 

Another method for preparing 2-phenylbenzofurans through o-hydroxydeoxybenzoins (without isolating the latter) is the rearrangement of diazoacetophenones with a copper catalyst in the presence of phenol in benzene,400 which gives directly 63% phenoxyacetophenone and 26% 2-phenylbenzofuran [Eq. (1)]. 

Trimethoxydiazoacetophenone undergoes acid-catalysed cyclization to give 4,6 - dimetho xy- 3 (2H) -ben zo fu rano ne.5 7 Under the same conditions diazoacetophenone gives tlie intermolecular product 2-hydroxyacetophenone. The difference in reaction mechanism was attributed to the interaction of o-OMe with the diazomethyl group. 

This linear polymerization represents one unusual case of diazoacetophenone oxidation. For instance, upon the action of copper oxide, diazoacetophenone gives the ketocar-bene, which is involved in typical carbene reactions—dimerization, addition to olefins, insertion in the O—H bonds of alcohols, etc. If the amine cation radical is used as an oxidant instead of copper oxide, only the polymer is formed. The ketocarbene was not observed, despite careful search (Jones 1981). 

The asymmetric induction on the 1,3-dipolar cycloaddition reaction of carbonyl ylides has also been studied using chiral dipolarophile. The Rh2(OAc)4-catalyzed reactions of o-(methoxycarbonyl)diazoacetophenone 89 with enantiomerically pure vinyl sulfoxides 103 afforded 4,10-epoxybenzo-[4,5]cyclohepta[l,2-c]furan-3,9-dione 105, in good or moderate yield with complete regioselectivity [113]. The endo stereoisomer 105a is favored with respect to the exo isomer 105b and interestingly, high diastereoselectivity and complete enantioselectivity have been achieved (Scheme 32). 

Potassium hydroxide 2-Diazoindan-l,3-diones from o-cyano-co-diazoacetophenones via 8-oxoindeno[l,2-d]triazoles... 

Preparation by hydrolysis of o-acetoxy-a-acetoxy-acetophenone (SM) with aqueous potassium hydroxide solution by gently wanning for 10-15 min on a water bath maintained at 80° (71%). SM was obtained by cupric chloride-catalyzed decomposition of o-acetoxy-a-diazoacetophenone in dioxane solution in the presence of acetic acid (65%, m.p. 161-162°) [5137]. 

The intramolecular carbenoid-carbonyl cychzation has been one of the most effective methods for generating cyclic carbonyl yhdes, since Ibata and coworkers reported the transition metal-catalyzed decomposition of o-alkoxycar-bonyl-a-diazoacetophenones in the presence of various... 

The reaction was carried out by adding a solution of o-methoxycarbonyl-ct-diazoacetophenone in CH2CI2 over aperiod of 1 h to a suspension of the PyBOX-i-Pr-Sc(OTf)3 complex (10mol%), MS 4A, Rh2(OAc)4 (2mol%), and benzyloxyacetaldehyde derivatives in CH2CI2. 

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