Silver oxide reaction with acyl chloride

The classical Hunsdiecker reaction (equation 18), involving the reaction of silver carboxylates with halogens, and the various associated side reactions, has been reviewed several times. Optimum yields are obtained with bromine, followed by chlorine. Iodine gives acceptable yields provid that the correct stoichiometry of 1 1 is used. The reaction is most frequently carried out in tetrachloromethane at reflux. From a practical point of view, one drawback is the difficulty encountered in the preparation of dry silver carboxylates the reaction of silver oxide on the acyl chloride in tetrachloromeAane at reflux has been employed to circumvent this problem. Evidently the use of molecular bromine limits the range of functional groups compatible with the reaction the different reaction pathways followed by the silver salts of electron poor (equation 19) and electron rich (equation 20) aryl carboxylates illustrate this point well. 

When nitration of pyridazine iV-oxides is carried out with acyl nitrates (prepared in situ from acyl chlorides and silver nitrate) the reaction takes place at the /3-position relative to the iV-oxide group. Under these circumstances only mononitro derivatives are formed. For example, nitration of pyridazine 1-oxide with acetyl nitrate yields 3-nitropyridazine 1-oxide (17%) and 5-nitropyridazine 1-oxide (0.8%), whereas with benzoyl nitrate a better yield of 5-nitropyridazine 1-oxide is obtained. 

Many of the reactions of amines are familiar from past chapters. Thus, amines react with alkyl halides in S 2 reactions and with acid chlorides in nucleophilic acyl substitution reactions. Amines also undergo E2 elimination to yield alkenes if they are first qualernized by treatment with iodomethane and then heated with silver oxide, a process called the Hofmann elimination. 

In an extension of this method, Koenigs and Knorr subsequently reported that reaction between acylated glycosyl halides (bromides, chlorides, or iodides) with alcohols, in the presence of silver promoters (oxide or carbonate) furnished 1,2-trans alkyl glycosides. 

Oxidation of sulfides to sulfoxides. This well-known nitrating agent has been found to be a suitable reagent for oxidation of sulfides to sulfoxides without frirther oxidation to sulfones. The reaction is carried out at 0° yields are generally in the range of 80-1007<>. Surprisingly the reaction is faster than that with peroxy compounds. In the case of sulfoxides that tend to give Pummerer-type reactions with ACaO, benzoyl nitrate is the preferred oxidant. This acyl nitrate is prepared from benzoyl chloride and silver nitrate it is somewhat more reactive than acetyl nitrate, and oxidations can be conducted even at —76°. 

Wilds and coworkers have discussed the influence of highly hindered acyl chlorides on the Arndt-Eistert synthesis. The diazomethanes derived from such acyl chlorides fail to rearrange normally with any of the three conventional catalysts, silver oxide-methanol, silver benzoate-triethylamine-methanol, or tertiary amines-high-boiling solvents. Under special reaction conditions, abnormal reaction products were isolated. 

Codeposition of silver vapor with perfluoroalkyl iodides at -196 °C provides an alternative route to nonsolvated primary perfluoroalkylsilvers [272] Phosphine complexes of trifluaromethylsilver are formed from the reaction of trimethyl-phosphme, silver acetate, and bis(trifluoromethyl)cadmium glyme [755] The per-fluoroalkylsilver compounds react with halogens [270], carbon dioxide [274], allyl halides [270, 274], mineral acids and water [275], and nitrosyl chloride [276] to give the expected products Oxidation with dioxygen gives ketones [270] or acyl halides [270] Sulfur reacts via insertion of sulfur into the carbon-silver bond [270] (equation 188)... 

Two alternate approaches to eudistomin T (17) have appeared, both of which also provided a route to eudistomin I (8). VanWagenen and Cardellina treated isonitrile 152 (Scheme 6) with the appropriate acid chloride (153) to yield the a-ketoimidoyl chloride 154 (or 155), which underwent silver ion mediated cyclization to the p-carboline ring system (122). Wasserman and Kelly (123), on the other hand, used acid chlorides 153 (Scheme 7) to acylate triphenyl-phosphine 156. Subsequent condensation of tricarbonyl 158 (R = benzyl), from ozonolysis of 157, with tryptamine, followed by oxidization yields eudistomin T. Eudistomins I (8) and M (13) were also obtained by the latter, tricarbonyl, method (123) eudistomins M and A (12) were obtained, by Molina s group in Spain, utilizing an aza-Wittig reaction (124). 

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