Lead tetraacetate nitriles

The Cg-amine, originally obtained by the methanolysis of kasugamycin, on treatment with lead tetraacetate or sodium periodate afforded a nitrile amine, with evolution of carbon dioxide, showing a maximum at 2200 cm.-1. This reaction is explained only by the structure (13). The -N-C=N group of the product can be formed by oxidative decarboxylation and can be easily rationalized by the present understanding of such reagents (2, 13) as shown below. On the other hand, the treatment... 

Vinylic copper reagents react with CICN to give vinyl cyanides, though BrCN and ICN give the vinylic halide instead." Vinylic cyanides have also been prepared by the reaction between vinylic lithium compounds and phenyl cyanate PhOCN." Alkyl cyanides (RCN) have been prepared, in varying yields, by treatment of sodium trialkylcyanoborates with NaCN and lead tetraacetate." Vinyl bromides reacted with KCN, in the presence of a nickel complex and zinc metal to give the vinyl nitrile. Vinyl triflates react with LiCN, in the presence of a palladium catalyst, to give the vinyl nitrile." ... 

Aldoximes can be oxidatively dehydrogenated to nitrile oxides using a variety of oxidants such as lead tetraacetate [16a], alkali hypohalites [lla],NBS in DMF followed by base treatment [16b], chloramine-T [11b], 1-chlorobenzotriazole [16c], mercuric acetate [ 16 d], etc. However, we employed either NaOCl or chloramine-T for most of our INOC reactions. For instance, a piperidine ring fused to an isoxazoline as in 14 was constructed using the INOC methodology (Scheme 3) [17]. Monoalkylation of N-tosylallylamine 10 with the bromoacetal... 

The diacetamide compounds were regularly obtained in all degradations employing ammonia with or without silver oxide until Hockett and Chandler applied the method to hexaacetyl-D-gluco-D-flruZo-heptono-nitrile (XLIX) and obtained a monoacetamide derivative that was identified as iV-acetyl-D-glucofuranosylamine (L). The furanose structure of L was established by lead tetraacetate oxidation. They... 

Reaction of 2-amino-5-aryl-thiadiazole (88 R = Ar) with aryl nitriles in the presence of aluminum chloride produced the aryl amidine (89) which was oxidized with lead tetraacetate to yield the 2,6-diaryl-[ 1,2,4]-triazolo[5,1 -( ]-1,3,4-thiadiazoles (90) <91 UC(B)435>. 

The oxidation of hydrazones 143 provides, in principle, a very convenient route to nitrile imines from easily accessible starting materials. However, the earliest reagent used, lead tetraacetate, was of limited effectiveness as yields were low and the reaction often gave high yields of diacyUiydrazides as byproducts. Work has been done on the apphcation of several other oxidants to this process to produce a more effective general route. The one that has proved most popular is chloramine T (A(-chloro-A(-sodio-p-toluenesulfonamide, CAT) which is used under mild conditions and has been shown to work well for both cycloaddition (79) (e.g., in the preparation of 146 from 145) and electrocychzation (80) reactions. 

Enantiomerically pure nitrile imines (211) have also been generated by the lead tetraacetate oxidation of aldehydo sugar p-nitrophenyl hydrazones. Reaction with methyl acrylate gave the pyrazolines as a 1 1 mixture of the (55) and (5R) epimers, which were resolvable in some cases (116). 

Primary amines at a primary carbon can be dehydrogenated to nitriles. The reaction has been carried out with a variety of reagents, among others, IF5,"9 lead tetraacetate, 20 nickel peroxide,121 NaOCl in micelles,122 S g-NiSO, 2-1 and CuCl-02-pyridine.124 Several methods have been reported for the dehydrogenation of secondary amines to imines.125 Among them126 are treatment with(l) iodosylbenzene PhIO alone or in the presence of a ruthenium complex, 27 (2) Me2SO and oxalyl chloride, 2" and (3) f-BuOOH and a rhenium catalyst. 29... 

Direct dehydrogenation of oximes is also possible, particularly for sterically hindered nitrile oxides. The most successful oxidizing agents are alkaline hypobromite and NBS in the presence of base, the latter being valuable when basic groups are present. Lead tetraacetate and alkaline hypochlorite have also been employed, but the yields are lower. The formation of furoxans from the reaction of alkoximes with nitrogen oxides is believed to proceed via the corresponding nitrolic acids. 

Many reagents convert primary amines into nitriles. Some of these have been mentioned above and represent serious limitations on methods for generating carbonyl compounds. Other ways of oxidizing amines to nitriles are the use of nickel peroxide,lead tetraacetate," copper(I) chloride plus oxygen and pyridine," iodine pentafluoride and benzeneseleninic anhydride. double bromination-dehy-drobromination can be effected for the preparation of nitriles with 2 equiv. of NBS and trimethyl-amine. Likewise, fluorination and elimination of HP gives nitriles." ... 

Lead tetraacetate oxidizes oximes to various products. For exanqrle, the oxime of cyclohexanone gives a-acetoxynitrosocyclohexane in 35% yield.Aldoximes react with lead tetraacetate to give nitrile oxides which then yield acetyl hydroxamates 1 reaction with acetic acid. ... 

Trimethylsilyl azide, (TMSN3) reacts with carbon-carbon double bonds to form a compound which can be cleaved by lead tetraacetate (or phenyliododiacetate) to yield a carbonyl and a nitrile, as in equation (37).The reagent has been tqrplied extensively to the cleavage of unsaturated steroids, as illustrated in equation (38). 

Lead acetate azides, Pb(OAc)4 (N3)n, prepared in situ from lead tetraacetate and azidotrimethylsilane, react with alkenes to yield a variety of products, depending on the structure of the alkene 1,2-diazides. 1,2-acetoxy azides, a-azido ketones, allylic azides, and <5-oxo nitriles (by the oxidative cleavage of cyclohexene rings)97. The diazides and acetoxy azides are formed by preferential syn addition, but the diastereoselectivity (up to 3 1) is far from satisfactory with both acyclic and cyclic alkenes98,99. 

Niemann and Hays later showed that the oxidation of one mole of iV-acetyl-D-glucosylamine by lead tetraacetate involves the slow consumption of slightly more than two moles of oxidant, so confirming the result of periodate oxidation. Hockett and Chandler prepared an isomeric N-acetyl-D-glucosylamine, also cyclic since it gives a tetraacetate, by the action of 29 % aqueous ammonia on aldehydo-D-glucose pentaacetate or on hexa-0-acetyl- a -D-glucoheptonic nitrile. The oxidation of this isomer produced formaldehyde (isolated as its 2,4-dinitrophenylhydrazone), but... 

Primary amines at a primary carbon can be dehydrogenated to nitriles. The reaction has been carried out with a variety of reagents, among others, lead tetraacetate, NaOCl, ... 

More intensive dehydrogenation of primary amines having two hydrogen atoms on the adjacent carbons leads to nitriles. Such dehydrogenations are accomplished by argentic oxide cobalt peroxide [1136], nickel peroxide [936], lead tetraacetate [443, 444], sodium hypochlorite [692], potassium ferricyanide [924], and potassium ruthenate [196] (equation 513). 

Lead tetraacetate oxidizes primary amines containing an a-methylene group to nitriles, probably through the aldimine. Yields are nearly doubled when the ratio of amine to oxidant is 1 2, but even so the highest yield reported Is 61%. A perhaps... 

In the first reported reaction of benzyne with oxazoles, the isolated products were 2 1 benzyne oxazole adducts. In that reaction, the benzyne was generated in situ in a thermal process carried out at 101 °C. The initially formed adduct loses a nitrile to give an isobenzofuran, which adds a second molecule of benzyne. When benzyne is generated at 0°C from 1-aminobenzotriazole and lead tetraacetate under dilute conditions, the initial cycloadducts (59) are formed in essentially quantitative yield <90JOC929>. They can be handled at room temperature and can be decompose at elevated temperatures to isobenzofuran (60), which in the presence of other dienophiles leads to a variety of useful products (Scheme 16). 

Synthesis of phenols and aromatic nitriles.3 In a new phenol synthesis, an aromatic hydrocarbon is first thallated with the reagent in trifluoroacetic acid to give an arylthallium ditrifluoroacetate (which can be isolated) and then oxidized with lead tetraacetate in the presence of 1 equivalent of triphenylphosphine. The resulting aryl trifluoroacetate is then hydrolyzed with dilute base. The triphenyl-... 

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