Diazo acetamides

Afonso, Gois, and co-workers followed this report with an unexpected decarbonylation of diazo-acetamides (Scheme 9.14) using 43-NHC (Fig. 9.8) [58]. The reaction generated three different products, with low selectivity for the decarbonylated product. The authors tested other substrates with different R groups and bulk at the amine position but found no correlation to the amount of decarbonylation product formed. However, 43-IPr was more selective than 43-SIPr for the decarbonylation product. The authors attributed the decarbonylation to the axial coordination of the NHC ligand to the dirhodium (11) complexes. 

Scheme 9.14 Decarbonylation of diazo-acetamides with catalyst 43-NHC...

This group was used as a bulky protective group to the intramolecular C-H insertion of a-diazo acetamides and in directed orthometalation reactions of aryl amides. The cumyl group is readily cleaved with CF3CO2H. Formic acid has also been used to remove a cumyl group. 

The range of diazo compounds that can be used in this catalytic cycle is limited. Diazomethane is not compatible with the system as diazo dimerization occurs instead of ylide formation [16,17]. Diazoacetates cannot be used as the corresponding sulfur ylides are too stable and are known not to react with simple aldehydes [ 18,19,20,21 ]. As it was known that sulfur ylides stabilized by amides are sufficiently reactive to add to aldehydes [18,22,23,24,25], diazo acetamides... 

Catalytic cyclopropanation reactions with disubstituted diazo esters are discussed in the following sections, R1C( = N2)C02R2 R1 = CF3 Section 1.2.1.2.4.1., R1 = R3CO, this section R1 = SiRl, Section 1.2.1.10. R1 = N02, Section I.2.I.8.3. R1 = P(0)Ri Section 1.2.1.9, Some examples of catalytic cyclopropanation reactions with diazo acetamides are given in Table 14. In reactions with a-diazo-A,A-dimethylacetamide catalyzed by tetraacetatodirhodium, cyclopropane yields decrease with decreasing alkene reactivity (ethoxyethene, 82% styrene, 47% cyclohexene, 21%),164,258 Furthermore, with A-alkyl substituents larger than methyl, intramolecular carbenoid C-H insertion is in competition with alkene addition, e.g, formation of 4.164,259... 

Diazo transfer from tosyl azide to diphenylphosphinoxide acetamide (33) is accomplished via 1,5 ring closure of 34 to afford 4-diphenylphosphinyl-5-hydroxy-l,2,3-triazole (35).14 However, triazole 35 is further thermally isomerized in DMF back to diazo acetamide (34). Tosyl azide in the presence of piperidine converts phosphinoxide acetophenone (36) to diazo acetophenone 37.15... 

Homologation-condensation. 3-Acyltetramic acids are accessible from N-acylacetylglycine esters. In turn the latter compounds may be assembled from a-diazo acetamide derivatives and aldehydes with elimination of dinitrogen. Zirconium chloride is a useful catalyst. 

Dinuclear rhodium(II) complexes were tested as catalysts for intramolecular C-H insertions of diazo-acetamides. In this study, the reactivity of axially monocoordinated [(NHC)Rh2(OAc)4j complexes was found to be different... 

Catalytic N-H insertion reaction of diazo acetamides has been reported using Ru(II) complex (114) as catalyst.ios... 

The Friedel-Crafts acylation of acetanilide with chloroacetyl chloride yields l-acetamido-4-chloroacetylbenzene. The trimethylammonium group is introduced by reaction with trimethylamine, followed by hydrolysis of the acetamide group. This diazo component is a constituent of numerous yellow, orange, and red cationic azo dyes. Using diethyl- m-toluidine as the coupling component, the lightfast red dye 35 [67905-12-8] is obtained [99],... 

Several different methods have been employed for the preparation of diazo(trimethylsilyl)meth-ane (l).14 At present, the best synthetic method seems to be the diazo transfer reaction between diphenylphosphoryl azide and (trimethylsilyl)methylmagnesium chloride.15 However, the product often contains (chloromethyl)trimethylsilane and hexamethyldisiloxane as impurities. This method can also be employed for the synthesis of diazo(triethylsilyl)methane and diazo(di-ethylmethylsilyl)methane.16 The diazo transfer reaction can also be carried out with (trimethyl-silyl)methyllithium and tosyl azide.17 Other methods are the silylation of diazomethane with (trimethylsilyl)trifluoromethanesulfonate18 or chloro(trimethyl)silane19 and the base-induced cleavage of iV-nitroso-A-[(trimethylsilyl)methyl]urea or the related carbamate or acetamide.2 0a e... 

C2-homologizati on of sugars with, 264-265 Acetamide, JV-bromo- (AcNHBr, NBA) bromohydrination with, 275-276, 287 Acetaminophen (= paracetamol), 301 Acetate, piperidinium cat. for aldol add., 82 —, sodium a-epimerization of ketones, 277 opening of oxiranes, 282 Acetic acid, anhydride (AcfO) protection with. See Protection Pummerer rearr. with, 51, 265 —, esters (See also Protection of hydroxy groups) C-H acidity, 10 1-methylethenyi ester pr., 174 transenolization, 58 —, bromo-, esters pr., 179 a2-synthon, 19, 65, 309 d2-synthon, 19, 301 —, chloro-, esters pr., 179 hydantoins from, 308 —, cyano-, esters pr., 177 pyrrolines from, 298 —, (dialkoxyphosphinyl)-, esters pr 188 Wittig-Horner olefinations, 267, 282 —, diazo-, ethyl ester pr, 176, 178 cyclopropanes from, 74—75 —, dichloro- deblocking of pixyl ethers, 342 —, hydroxy-, esters pr., 176 —, hydroxyphenyl-, (S)- (l-mandelic acid) ... 

The thiazetine (49) is in thermal equilibrium with the ring-opened heterodiene (50), and on exposure to Sb2Te3 at elevated temperature gives the novel A -l,2,4-thiatellurazoline system (51). A number of 1,2-thiazetine 5-oxides (52) have been prepared by thermolysis of diazo-ketones in the presence of A-suIphinyl-amines and from the reaction of 2-acyl-acetamides and thionyl chloride in the presence of base/ l,2-Thiazet-2-yls (53), a new class of stable radicals, are obtained by photolysis and thermolysis of (54) and sulphur amides, for example (55). They are useful as catalysts, regulators, or inhibitors in radical-initiated reactions. ... 

Sodium acid methanearsonate Methane base. See Bis (p-dimethylaminophenyl) methane Methane, bis (2-(2-butoxyethoxy) ethoxy)-. See Butylcarbitol formal Methanebis (N,N -(5-ureido-2,4-diketotetrahydroimidazole)-N,N-dimethylol). See Imidazolidinyl urea Methane, bromochloro-. See Bromochloromethane Methane, bromochlorodifluoro-. See Bromochlorodifluoroemethane Methane, bromodichloro-. See Bromodichloromethane Methane, bromotrifluoro. See Trifluorobromomethane Methanecarbonitrile. See Acetonitrile Methanecarboxamide. See Acetamide Methanecarboxylic acid. See Acetic acid Methane, chloro-. See Methyl chloride Methane, chlorodibromo-. See Chlorodibromomethane Methane, chlorofluoro-. See Chlorofluoromethane Methane, compressed. See Methane gas, Methane cyanine. See Malononitrile Methane, diazo-. See Diazomethane Methanedicarbonic acid Methanedicarboxylic acid. See,Malonic acid Methanedicarboxylic acid, diethyl ester. See Diethyl malonate... 

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